Aquarium species

Aquarium Species
an annotated list of temperate marine species
By Dr J Floor Anthoni, 2005
www.seafriends.org.nz/dda/aqua2.htm

The Seafriends aquarium ecosystems are small and suffer by hindsight from some design limitations such as lack of light. Because of this it is limited as to the number of species it can show and how large individual fish are. For practical reasons, those species that are difficult to keep or that are rather destructive to others, have been excluded. Furthermore, the aquariums are now being prograded to the highest level we can attain, enabling more sensitive species to live and grow. They have become an important part of our research in understanding the nature and workings of degradation, now the foremost threat to the sea. This annotated species list is interesting because it details our experience, good and bad. The Seafriends aquariums have always enjoyed intense interest because of its large number of species, kept harmoniously inside a true ecosystem.

. For suggestions and comments, please e-mail the author, Dr J Floor Anthoni.
-- Seafriends home -- DDA index page -- site map --Rev 20050630,20050805,

Species
By having a tank for each habitat type, the number of species that can be kept together in harmony is highest. Each habitat has the kind of sand that is found there and also the kinds of rock. Rocks have been arranged to provide shelter on various levels: in the sand, on top of the sand and higher still. They and the plants have been arranged such that territorial boundaries can be recognised easily. In this chapter we'll summarise all visible species that have been kept more or less successfully, together with a description of behaviour and problems associated with keeping them.

Some species provide valuable services such as habitat cleaning and grooming, and they have been placed also in habitats where they are normally not common. Typical of these are sea cucumbers, cushion stars, various grazing snails, hermit crabs and sometimes sea urchins.

mud flats: the sheltered places inside estuaries where mud has a chance to settle. Mud has very fine particles, mixed with nutritious micro algae, detritus and bacteria. Our mudflat tank has 10-15cm of mud and muddy sand, which is well tunnelled through and does not turn putrid.

mangrove tree (Avicennia marina resinifera): NZ has only one species of mangrove tree, found only in the warmer reaches of the North Island. It is a flowering plant that manages to live miraculously in the salt water environment where it spreads long wandering roots. It needs much light and now and then fresh rain. In our aquariums they have never been doing well, usually wilting away after six months but may respond to improved water quality.
eelgrass (Zostera nana): the eelgrass is found in the sandy reaches that are exposed to wind. It grows from the high tide mark down to several metres under low tide, although this is not common inside estuaries. Eelgrass with its wandering roots needs to grow well to cope with all the tunnelling underneath it. In our aquariums eel grass withers usually after several months.
Neptune's necklace (Fosterygion lapillum): the necklace weed is often caught between mangrove roots, able to stand hours above water each day. In our aquariums it suffers the same fate as eelgrass.
triplefins: various species of triplefin can stay alive because they dig breathing holes in which they survive low tide. The common triplefin (Fosterygion lapillum) and the estuarine triplefin (Grahamina nigripenne) survive quite happily.
suckerfish (unidentified sp): NZ has an unidentified species of estuarine suckerfish that is well at home and easy to keep.
tunnelling mudcrab (Helice crassa): the tunnelling mud crab is easy to keep although it is easily predated upon by larger crabs. Inside the tank there is enough living space for about half a dozen. These crabs can live long and grow too large for the tank.
stalk-eyed mudcrab (Hemiplax hirtipes): the stalk-eyed mudcrab is not as easy to keep as the tunnelling mudcrab and requires a higher quality of water.
hairy-handed crab (Hemigrapsus crenulatus): the hairy-handed crab is easy to keep but it grows fast, becoming a menace to others. For peace and tranquility in the tank it is better to leave it out.
pillbox crab (Halicarcinus lacustris and H. whitei): pillbox crabs are slow-moving creatures that do not live very long. They feed from detritus and mud and little is known about them. They seem easy to keep but have the habit of disappearing.
porcelain crab or half crab (Petrolisthes elongatus): this crab is easy to keep as it tolerates poor water quality. It keeps itself hidden in cracks between stones from where it emerges during feeding or whenever something is done to the aquariums. By means of adapted mandibles with catch nets it waves about, it catches plankton and detritus on which it feeds. It is easily preyed upon. This crab adapts well to the mud flats, sand flats, deep estuary and sheltered reef.
New Zealand hermit crab (Pagurus novaezelandiae): the common hermit crab is both important and easy to keep. It is a very versatile feeder, living from surface scum or anything edible. It occurs in several habitats, and has been placed in most of our tanks. In the mudflats it burrows to survive at low tide. By burrowing, it perturbs the sea soil and helps aerate it.
snapping shrimp (Alpheus novaezealandia): the snapping shrimp lives inside the mangrove roots or under any stone. It is easy to keep but seldom comes out in the open. By placing some smaller stones near the glass wall, visitors can often see it at work because it likes to tunnel in the corner between glass and stone.
common shrimp (Palaemon affinis): this shrimp or prawn is common in several habitats as long as shelter is provided against wave action or strong tidal currents. It also occurs in rock pools. Being easy to keep and important because of its cleaning habits, we have placed it in tanks without large predators.
common cushion star (Patiriella regularis): the common cushion star is very easy to keep and important in cleaning habitats. By extending its stomach outside its mouth, it is able to live from many kinds of food, from diatom detritus to hairy algae on the glass windows and stones. But at a larger size it can become a predator, surreptitiously catching and killing prey like sea horses, flounder and clams. We return the larger ones to the sea. In the mudflat habitat it can stay alive outside the water for as long as it takes the tide to return.
mud snail (Amphibola crenata): the mud snail lives from the surface of the mud where fresh algae, detritus and bacteria are found. Even though these may be available, it is not easy to keep it alive for longer than a few months. It apparently requires a higher standard of water quality. One tank can maintain two to four mud snails.
mangrove snail or mudflat top shell (Diloma rostrata): the mangrove snail is easier to keep than the mud snail, but also requires good quality water. It competes with the mud snail for detritus, but clambers up the walls of the aquarium to graze hairy algae.
catseye snail (Turbo smaragdus): is easy to keep in all habitats and is also an important grazer and habitat cleaner. It does not like to be out of the water for prolonged periods. We placed this grazer in most tanks.
melagraphia or dark top shell (Melagraphia aethiops): the melagraphia or engraved snail lives half the time in the water and easily wanders out of the tanks. It is best kept in the tidal mudflats and sandflats, and is otherwise easy to keep in good quality water. When quality deteriorates, it spends more time out of the water.
horn shell (Zeacumanthus lutulentus): a small shell that lives from detritus. It is easy to keep but needs reasonable quality water.
green chiton (Chiton glaucus): the green chiton lives comfortably on the glass walls, where it burrows under the sand or mud. Only during the night does it come out to keep the difficult to maintain lower margin of the glass clean. We plan to place green one chiton for every 30cm of glass length.
oval bubble shell (Bulla quoyii): the common bubble shell is hardly ever visible, but at times it produces a spawning mass overnight. It manages to spread through the aquariums and their spawn mass gives them away. Although easy to keep, they require a moderately good quality of water.
southern olive (Amalda australis): this olive shell or plough shell folds its foot back over its shell, which allows it to slide through the sand, leaving slightly curving visible tracks. Visitors find it interesting to 'read' the tracks. It is relatively easy to keep but requires good water.
worms: various species of bristleworm or ragworm are visible through the glass windows, and they come out at feeding time when the tide is out.

sand flats: the sand flats are the places of the estuary where wind causes small waves that winnow the mud from the heavier sand grains, leaving a sand flat behind. Unlike mud, sand is not nutritious and does not stick together. Most organisms living here burrow and live inside cemented tunnels, which is not spectacular for aquarium visitors. In our aquariums the 7cm thick sand layer is inadequate for the deep burrowers, so we can't keep them. But the shallow burrowing clams like pipi and cockle can be seen from above.

triplefins : various species of triplefin can survive the low tide in little pools dug by them: common triplefin, estuarine triplefin.
parore (Girella tricuspidata): young parore are easy to keep as they tolerate quite poor quality sea water. Inside either the mudflat or sandflat tanks, they do not grow beyond 5-7cm.
sand flounder (Rhombosolea plebeia): although the sand flounder is not difficult to keep, it needs to be fed daily, which does not fit well with our schedules.
New Zealand hermit crab (Pagurus novaezelandiae): A very conspicuous species on the sand flats. See above.
waving hermit crab (Pagurus sp): the waving hermit crab has fine catch nets on its antennas, with which it catches phytoplankton. It also uses them to winnow fine particles from the coarse sand. It is a bit more demanding than the NZ hermit crab and requires a good quality of water.
NZ mantis shrimp (Lysiosquilla spinosa): although it normally tunnels deep, in the sand flats aquarium it builds extensive warrens in the shallow sand. This is a most adorable shrimp although at times hard to find. It also needs good quality water.
spider crabs (?): the sand flats have a species of camouflage crab which does not camouflage itself as its hairs trap mud. It thus has a muddy appearance. Easy to keep but also easily predated on by larger crabs.
paddle crab (Ovalipes catharus): the paddle crab is easy to keep but it is the most destructive of all species, leaving very little alive when kept. We have banned it as it also grows very fast, from 3cm to 10cm in one year.
pebble crab or big hand crab (Heterozius rotundifrons): because of its small size and slow growth, this crab is acceptable.
porcelain crab: see above.
other crabs: most crabs grow too fast and become too destructive to keep: hairy-handed crab, etc. see above.
common cushion star (Patiriella regularis): the cushion star is the most visible of all creatures and it is an excellent housekeeper. See above.
eleven-armed star (Coscinasterias calamaria): the eleven-armed star or prickly star is found on sand flats just under low tide where it hunts for burrowed clams. It is a very destructive predator and we can only keep the smallest, which are often difficult to find.
heart urchin (Echinocardium australe): the little NZ heart urchin lives almost permanently burrowed where it creeps around under the sand surface. It requires good water and has because of that disappeared from many estuaries. It maintains a current through two openings in the sand and lives from phytoplankton and detritus which it catches on a slime conveyor. Not easy to keep.
cake urchin or snapper biscuit (Fellaster zealandiae): a disc-shaped sea urchin with very short spines, capable of sliding through the sand just under the surface where it feeds on detritus. It needs good quality water and an ample supply of diatom scum. We have not yet been able to keep it longer than six months.
southern olive (Amalda australis): this olive shell or plough shell folds its foot back over its shell, which allows it to slide through the sand, leaving slightly curving visible tracks. Visitors find it interesting to 'read' the tracks. It is relatively easy to keep but requires good water.
horn shell: see above
catseye (Turbo smaragdus): is easy to keep and does well on the windows and rocks. see above
other grazing snails: melagraphia (Melagraphia aethiops) walks out easily, nerita (Nerita melanotrachus) needs very high quality water, which we were unable to supply.
whelks: whelks burrow in and through the sand and in doing so, contribute to its oxygenation. Scavenging whelks are needed to clean up dying and dead organisms.
chitons: various species of chiton can be kept successfully: green chiton (see above),
pipi (Paphies australis): requires good water
cockle (Austrovenus stutchburyi): paradoxically requires water of reasonable quality.
oysters: the two species of oyster found in the north need a reasonable quality of water with lots of food in it, which may be a contradictory requirement. On the one hand we like the aquariums to have little biodensity, but oysters and mussels require high biodensities in order to survive. Fortunately for the oysters, the sand flats have a much higher phytoplankton production than the other tanks, particularly in summer. The mussels we helped by placing them before the inlets, which assists them in catching food.

deep estuary: the deep estuary is permanently under water and the tide is important only for the currents it brings. Particularly near the entrances of estuaries, one finds an interesting and often very rich community of species.

flexible weed or tangle weed (Carpophyllum flexuosum): one of our most hardy seaweed species, but even so hard to keep when bacterial attack is high. This seaweed deals with deposition (mud) by sliming it off, but it is sensitive to decomposers.
velvet weed (Codium sp): is a pretty branched seaweed but needs good quality water.
parore (Girella tricuspidata): a most adorable fish and easy to keep, even in poor quality water. Parore are plant eaters and their fused teeth allow them to scrape algae from the glass and rocks. They can quickly clean up a heavily fouled tank.
triplefins: common triplefin, estuarine triplefin.
Grahams gudgeon (): difficult to find but relatively easy to keep. It looks like a large freshwater bully.
short-finned eel (Anguila australis schmidti): despite its reputation, a most adorable fish and easy to keep. Give it space under a rock and it will eventually take food by hand. It is a very peaceful animal.
sweep (Scorpis lineolatus): the sweep or grey maomao is easy to keep as it tolerates poor quality water. It is an energetic little fish that grows relatively slowly. A few are needed to achieve schooling. Sweep are very playful and fast swimmers and appreciate an obstacle course of holes, channels and obstructions that they can swim through and dodge at high speed while chasing one another for fun. They also require a large share of food. We keep a good watch on their bellies. Fortunately they are also fast feeders, planning their attack runs on food particles, which secures them the share they need.
spotty (Notolabrus celidotus): spotties are easy to keep and they are happy to live together with other spotties and other fish. They tolerate poor water conditions.
other fish: the deep estuary invites for energetic fish like trevally (Pseudocaranx dentex) and jack mackerel (Trachurus novaezelandiae). In aquarium conditions with a limited supply of food, these grow sufficiently slowly to keep for two to three years. The common estuarine yellow-eyed mullet (Aldrichetta forsteri) does not survive in small tanks. Note that in a small ecosystem like ours it may not be possible to keep highly energetic fish and at the same time high quality water.
porcelain crab: see above.
blackfinger crab (Ozius truncatus): although rather peaceful, this crab is nonetheless able to cause a lot of damage, particularly during the night. Because it hides by day, it is not a good trophy for visitors.
piecrust crab (Cancer novaezelandiae): it is not easily found but in the aquariums an acceptable powerbroker although it cracks mussels and grazing snails, particularly at night when nobody watches. We do not have much experience with these, although one is still alive and healthy in the quarantine tank. It may have to be returned to the sea.
cushion star: see above.
sea cucumber (Stichopus mollis): one of the most important creatures in our tanks as it removes dust and detritus from all objects, including plants and sponges. Each tank should have two of these.
green-lipped mussel (Perna canaliculus): we have not yet proved to keep these under the new regime of water quality first. These mussels need high densities of phytoplankton, and failing this, need a current that assists them in their filter feeding.
nesting mussel (Modiolarca impacta): has disappeared from many places and is not easy to get.
horse mussel (Atrina pectinata zelandica): the horse mussel or fan mussel needs very deep sand which is not available. When not completely covered, it easily falls prey to crabs. Difficult to keep.
catseye snail: see above. Easy to keep and a necessary grazer.
cooks turban snail (Cookia sulcata): a tenacious grazer that likes good water quality and a run for itself. By grazing hard, it apparently also promotes the growth of hardy algae that can not be grazed by the catseye snail and others. Not even by our scraping window cleaning magnets. It is easy to keep but can easily be predated on by crayfish and spotty.
screw shell or turret shell (Maoricolpus roseus): is not easy to keep as it requires reasonable quality water and is easily cracked by crabs. It has the strange habit of disappearing underground when the sand moves, as it is not able to burrow actively. Being totally immobilised, it feeds from plankton.
lined whelk (Buccinulum pallidum powelli): is a scavenger and deserves to be in every aquarium. It cleans up dead animals together with cushion stars but also comes out at feeding time. It is very easy to keep and benign to others.
speckled whelk (Cominella adspersa): the cominella is a sturdy whelk that cannot entirely be trusted, since it also predates a little. By burrowing frequently, it helps oxidise the deeper layers of the sand. It is easy to keep.
chitons: green chiton (Chiton glaucus), noble chiton (Eudoxochiton nobilis), snakeskin chiton (Sypharochiton pelliserpentis), butterfly chiton (Cryptoconchus porosus). All easy to keep but with variable success in the long term.
bubble shell: see above.
seasquirts: seasquirts survive well in moderate water quality, but they need a good supply of phytoplankton. The blue-white Asterocarpa coerula is easy to keep.
sponges: the most common sponges of the deep estuarine environment are meatball sponges (Aaptos spp), and these do well in moderately healthy water. However, in 2004 all died.

sheltered reef: the sheltered reef is one of the most interesting of marine environments because of its abundance in peaceful organisms. The sheltered reef tank also functions as a refuge for slow feeders (like sea horses), and this bans most fish and most triplefins. We have allocated another rocky reef tank intermediate between the exposed reef and the sheltered reef, where all triplefins are welcome but not the larger fish such as spotty, leatherjacket and snapper. The sheltered reef stands out by its many seaweeds, which until 2004 we have not been able to keep and grow. This has now become a main focus of the new management regime.

stalked kelp (Ecklonia radiata): the stalked kelp is the most common of seaweeds along NZ coasts, often covering vast underwater forests. However, it is surprisingly difficult to keep in an ecosystem, as it is rather sensitive to bacterial attack and is highly appreciated by strong grazers like cooks turban shells and sea urchins.
featherweed (Carpophyllum flexuosum): a fluffy seaweed with feathery thin leaves, held upright by its float bladders.
shallow bladderweeds: wireweed (C. angustifolium), bladderwrack (C. maschalocarpum) need too much light and wave action, and may never be kept successfully.
sausage weeds (enteromorpha spp): are for unknown reasons difficult or impossible to keep.
sea rimu (): sea rimu is normally associated with remote islands and clear water, but it became one of the first to show growth in our new regime of progradation.
other green seaweeds: sea lettuce () grows in degraded environments but escapes the attack from bacteria partly by living on the water's edge. It is easily grazed and we have not yet been successful growing it. Also too many species like eating it. Green grapeweed (Caulerpa geminata) has wandering roots and may well be suitable, but is now hard to find.
red seaweeds: the red seaweeds have shown themselves rather keen on good water quality but the pinkish transparent Pterocladia lucida is one of the first to grow. We plan to introduce new species gradually to test whether they survive because red and green seaweeds are very festive.
triplefins: nearly all triplefins are welcome in the sheltered reef tank, as they are able to sort out their territorial differences. But we have to separate the larger ones (variable triplefin) to tanks with larger fish. But the tanks also need to be split to accommodate slow feeding animals (sea horse, bigeye, slender roughy)
bellied sea horse (Hippocampus abdominalis): people always ask for the sea horses but we had to give up on them, because their natural food of mysid shrimps became rare and could no longer be depended on. But it is possible to have some artificially bred sea horses that have grown used to eating non-living food.
night fish: bigeye (Pempheris adspersus) is relatively easy to feed as long as a supply of mysid shrimps is available from local estuarine creeks. The same goes for the slender roughy (Optivus elongatus), also a most delightful fish. These fish live in the slow lane, and do not require much food. Give them a cave under an overhang, and they can be seen by visitors. The rock ling is also a night fish but eventually becomes capable of eating rather large fish. Its place is the sin bin with the coastal dwarf scorpionfish.
suckerfish: the small suckerfishes are delightful creatures but are not easy to keep as they require clean water and a protected place because they too are slow feeders. Various species should be reasonably easy to keep (but difficult to catch): lump fish (Trachelochismus pinnulatus), orange clingfish (Diplocrepis puniceus), urchin clingfish (Dellichthys morelandi). The urchin clingfish lives a cryptic life not just underneath large sea urchins but inside the smallest cracks. All clingfish are sensitive to predation and must not be placed in tanks with fish bigger than them.
weedfish: weed fishes are also delightful and well camouflaged. They need a secure prison because they are rather adventuresome and escape through small openings. Brown topknot (Notoclinus compressus), topknot (Notoclinus fenestratus), crested weedfish (Cresticeps aurantiacus) a spectacular possession.
camouflage crabs (Notomithrax ursus and Notomithrax peroni): visitors delight in camouflage crabs because they are so well camouflaged by nipping bits from seaweeds and gluing these onto their hairs. The two species live well together, but they don't live for long. After three years they die. Camouflage crabs can make a real mess of seaweeds and their number may need to be limited for this reason. Two to three per tank are tolerable.
porcelain crab: see above. These need cracks to shelter in, and because of this their numbers are limited. Porcelain crabs live for several years, becoming a fine porcelain blue when old.
other crabs: the large crabs of the rocky shore such as the purple shore crab (Hemigrapsus edwardsi, Leptograpsus variegatus) and the red rock crab (Plagusia chabrus) are too destructive to keep. But the smooth scarlet swimcrab (Nectocarcinus bennetti) and hairy scarlet swimcrab (Nectocarcinus antarcticus), that come out by night, are borderline cases because they fortunately stay small and have few requirements. The hairy crab (Pilumnus novaezelandia) is also cryptic but quite innocent and is a delight once visitors find it. The triangle crab (Eurynolambrus australis) is nocturnal but delightful and harmless and easy to keep in moderate quality water.
common prawn (Palaemon affinis): a spectacular creature which is easy to keep and does not require to be fed (but they will be the first ones to find the food).
painted prawn (Alope spinifrons): the painted prawn does not swim around but is spectacularly coloured (blue/red) and can grow to 10cm long. Although it has now become hard to find, it is easily caught inside rock pools and keeps well. It pays to find a breeding couple. It is at risk in tanks with fish larger than itself.
killer prawn (Ibaccus alticrenatus): the killer prawn is found at night in sheltered deep water where it can be caught with some skill. It does well in the aquariums but requires good quality water. It is a slow feeder and may need attention at feeding time.
cushion stars: see above. The elevated cushion star or ambush star (Stegnaster inflatus) should be in the sheltered reef, but has shown itself rather destructive. As it stands tiptoed on its arms, it produces a shelter, sought after by unwary animals like grazing snails, and even sea horses. It then quickly closes up against the glass as it digests its victim outside its body. But these animals have spectacular colours and are easily kept. We keep them in the sin bin.
brittle stars: various species of brittlestar survive easily in moderate to good quality water as they filter plankton and detritus for food. They do so by extending their arms with sticky tubefeet outside their hideouts, catching whatever presents itself. As they do not need to be fed, they occupy an important place in the whole. The common brittlestar (Ophionereis fasciata) is easy to obtain and easy to keep. The oar star (Ophiopteris antipodum) is more demanding of good quality water.
green sea urchin (Evechinus chloroticus): a voracious grazer that must be observed carefully for the amount of plant damage it causes. One would be tempted to use small urchins, but these hide under stones, which is not attractive for visitors. Some sea urchins are definitely needed, but in a careful balance with other grazers.
greenlipped mussel (Perna canaliculus): see above. It needs reasonably good water and a current flow.
bearded or hairy or brown mussel (Modiolus aerolatus): the bearded mussel is hard to see because it encourages other organisms to grow on top. It needs good quality water to thrive. Although easy to catch, they have become rather rare.
paua or abalone (Haliotis iris): the paua is a spectacular animal when seen in action with its wide mouth flap and agility. It know the tanks well within a couple of weeks as it somehow memorises it. But it is also a voracious grazer, and able to eat the seaweeds faster than they grow. So small individuals have to be selected with care and then monitored for the damage they cause.
shield limpet (Scutus antipodes): an important detritus eater and a valuable and interesting animal. It is very easy to keep and occurs in several tanks. All shield limpets died in 2004.
other limpets: limpets seem easy to catch but they are easily damage and then die a week later. They have to be caught with surprise, which takes skill. Once an undamaged limpet is placed on the glass or rock and held there, it survives only in good water. They are very thrifty in their food uptake and can live happily in competition with other grazers.
grazing snails: see above for cooks turban, catseye, melagraphia. In the seaweed habitat a new number of grazers can be kept alive, like the opal shell (Cantharidus opalus), greenish topshell (trochus viridis) as long as an ample supply of healthy seaweed is available.
chitons: see above.
bubble shell: see above.
scavenging whelks: in all aquariums. Common whelk (Cominella glandiformis) , lined whelks (Buccinulum spp)
sea hares: sea hares are not easy to keep as they require a good supply of their flavour of seaweed and good quality water. The hairy sea hare (Bursatella leachii, Bursatella glauca) feeds on detritus and can be kept as long as water quality is moderate to good.
sea slugs: sea slugs are almost impossible to keep because they are all very specialised, often requiring sensitive species such as hydroids, sponges and bryozoa for food. The side-gill slug (Pleurobranchea maculata) is relatively easy to keep but it does not live long.
worms: various bristle worms will establish themselves and some are visible as they collect detritus into the heaps they create (bungy worms Timarete anchylochaeta).
sponges: pink golfbal sponge (Tethya ingalli) and golden golfball sponge (Tethya aurantium) and meatball sponges (Aaptos spp) are easy to keep but require good quality water.

exposed reef: the exposed reef is characterised by kelp forests and urchin barrens. The ability to grow stalked kelp (Ecklonia radiata) is thus important. In the exposed reef the larger fishes are kept but their number is limited by the amount of food they need.

stalked kelp (Ecklonia radiata): we have so far not been successful in growing this seaweed faster than it is eaten.
other seaweeds:
snapper (Pagrus auratus): snapper are relatively easy to keep because they are very hardy.
spotty (Notolabrus celidotus): see above. Spotties are very hardy and easy to keep
leatherjacket (Parika scaber): a delightful fish that is relatively easy to keep, requiring moderate quality water
kelpfish (Chironemus marmoratus): kelpfish are delightful aquarium animals but small ones are difficult to catch.
blue cod (Parapercis colias): blue cod are also quite delightful and intelligent but not as easy to keep and small ones are difficult to catch.
parore: see above.
crayfish (Jasus edwardsi): visitors like to see crayfish in the tanks, not realising that they are rather destructive. They also grow fast, so that a baby cray cannot be kept for longer than one year. Catching tiny crayfish is not easy.
red rock crab (Plagusia chabrus): although the red rock crab is primarily a plant eater, it does scavenge and predate as well. It grows very fast and cannot be kept for longer than half a year without becoming a nuisance.
sea urchin (Evechinus chloroticus): see above.
comb star (Astropecten polyacanthus): the comb star lives burrowed just under the surface of coarse sand where it feeds on a variety of prey and detritus. It needs sunlit sand and may need to be fed by hand to supplement its requirements. Small animals are not easy to obtain. It needs good quality water.
paua (Haliotis iris): see above.
shield limpet (Scutus breviculus): see above. Scutus are easy to keep and they help keeping the tanks clean.
dark rock shell (Haustrum haustorium): a fierce predator that catches grazing snails, particularly catseyes. We have banned it.
white rock shell (Dicathais orbita): as the dark rock shell, a fierce predator. Also banned.
whelks: scavenging whelks are in all aquariums. See above.
black sponge (Ancorina alata): although this sponge is found in degraded habitats, we have not been able to keep it.

deep reef: the deep reef habitat zone extends below the sun-lit zone of seaweeds down to the dark depths of the abyss. It is dominated by filterfeeders like sponges. Because of their weird shapes and colours, a sponge garden looks rather spectacular but it requires very good quality water. The deep reef aquarium does not open up to the sky but has been placed under fluorescent light simulating low light levels at depth. Because sponges filter plankton from the water, a large number of these could help filter the water for improved quality.

goatfish (Upeneichthys lineatus): goatfish are not easy to keep as they are easily damaged when caught, require good water quality and need to be fed frequently. We will try again.
triplefins: many species of triplefin can be accommodated in the deep reef, but most are difficult to catch.
other fish: the fish of the deep are almost impossible to catch and keep: banded perch, half-banded perch, butterfly perch, pink maomao, etc.
sponge crab (Petalomera wilsoni): the red sponge-carrying crab cuts a perfect disc from sponges such as the yellow Polymastia and carries this disc for protection on its back. Surprisingly, the cut sponge repairs itself quickly, and the bit carried on its back appears to thrive. These delightful crabs hide by day and are active by night, but they live for only 2-3 years. Easy to keep when water quality is very good and Polymastia sponges thrive.
brittle stars: see above.
snake star (Pectinura maculata): the red snake star is a spectacular creature and relatively easy to keep in good quality water. It feeds from all kinds of food.
bubble shell: see above.
tiger shell (Calliostoma tigris): this beautiful snail feeds only on specific sponges and cannot be kept without these. We have not been able to keep it.
carpet tubeworm (): the carpet tubeworm can be spectacular with is small white crowns but it has become hard to find, requiring good quality water.
sponges: five species are already thriving but more will be tried as water quality improves. Meatball sponges: see above. Yellow nipple sponge (Polymastia croceus): requires medium to good quality water. Its near-relative, the orange nipple sponge (Polymastia granulosa) is more demanding of water quality.
seasquirts: various species of seasquirt thrive in moderate to good quality water. Three species are thriving now and more will be tried, because they filter the water and thereby help to maintain water quality.
cup coral (Monomyces rubrum): requires good quality water but is otherwise easy to keep when not attacked by crabs or crayfish.

sin bin: the tank containing unexpected predators is affectionately called the sin bin. In nature a habitat exists which has several of these species, and we named it the shell trap. The shell trap occurs where the sandy beach meets the rocky shore. During storms, large numbers of shellfish are washed up the beach and many end up trapped in the crevices, gullies and the deeper water of the rocky reef, where they often continue to live. We find predators living here that are capable of existing from binge (after the storm) to famine (the period inbetween). Many are not just able to grow in the good times but also to shrink in the bad times. The sin bin is spectacular because of its many coloured anemones and starfish.

dwarf scorpion fish (Scorpaena papillosus): a delightfully camouflaged predator that is easy to keep in moderate quality water.
olive rock fish (Acanthoclinus fuscus): the rock fish belongs in the intertidal zone but because it is an active predator, has been placed here where it delights visitors.
rockling (): a small type of cod that does not grow large quickly. It needs good quality water.
prickly or eleven-armed star (Coscinasterias calamaria): the prickly star is a voracious predator and we can only keep very small ones. Fortunately they do not grow fast. Another variety exists, the half-n-half star that has the habit of splitting itself in order to multiply.
ambush star or inflated cushion star (Stegnaster inflatus): the inflated cushion star is also a fierce predator, capable of catching grazing snails and shrimps. But it is so gaudily coloured that it is a must to have several of.
cushion stars (Patiriella regularis): although scientists insist that there exists only one species of cushion star in NZ, one finds them quite different from harbour to harbour. We keep various colour varieties in the sin bin even though this animal is quite benign.
sea cucumber (Stichopus mollis): see above.
mud anemone (): a little brown anemone which is hard to keep because it does not grow old and keeps popping up here and there if water quality is moderately good. One cannot place it where one wants it.
olive actinia (Isactinia olivacea): the olive actinia is relatively easy to keep as it tolerates poor water quality (but it stops growing) and it grows old. We have two that are now over 13 years old. In good quality water it really thrives. They have recently doubled their numbers by splitting.
red actinia (Actinia tenebrosa): this spectacular and once common anemone is now hard to find. It likes good quality water and is normally found just under high tide mark in shaded places. It is not easy to keep. All but one died in 2004.
common or white-fringed anemone (Actinothoe albocincta): the common white anemone is easy to keep in good water quality. It is spectacular in numbers of white crowns on yellow/orange stems. They all died in 2004.
jewel anemone (Corynactis haddoni): has spectacular colour variations and can grow dense carpets of them. But it requires very good quality water and currents. We have not been able to keep it.
sand dahlia (Bunodactis sp.): is relatively easy to keep and grows old in good quality water.
rock pool dahlia (Isocradactis magna): occurs in spectacular colours from white to purple and orange to green. It grows old and large, and can tolerate poor conditions for a while. However for it to thrive, it needs good quality water. Because of its size it is a formidable predator and thrives in the shell trap habitat. We suspect that it needs sunlight to thrive, possibly because of photosynthesising zooxanthella in its tissues.
wandering anemone (Phlyctenactis tuberculosa): a large and spectacular anemone that wanders about in the tank. It is a formidable predator but not easy to keep as it requires good quality water.
sand octopus (Octopus gibsi), reef octopus (Pinnoctopus cordiformis): the octopus is a very endearing animal that can be kept for up to two years, since it is short-lived. But it needs its own tank as it is very destructive and an unequalled escape artist. When handled frequently, it becomes used to people and displays extraordinary behaviour such as touching hands, squirting water at the public and so on. Every octopus has its own personal character, we noticed. It is easy to keep but requires good quality water. As it grows fast, we have to return it to the sea when it is most endearing. Octopus need a lot of food and produce a lot of wastes, among which pure ammonia which is poisonous for some species. The bacterial filter is easily overloaded. We have now banned the octopus until further notice. Species it tolerates and does not molest are: starfish, sea urchin, sea cucumber, hairy sea hare, shield limpet, sponges, seasquirts.
trumpet shell (Charonia lampas rubicunda): the trumpet shell hunts for starfish and sea urchins and is a formidable predator causing loss of precious starfish. It has now been banned.
siphon whelk (Penion sulcata): the penion whelk is a fierce predator and is no longer welcome.