Small fish for reef tanks

When it comes to choosing fish for the reeftank, a shoal of small fish can be truly stunning, explains Les Holliday.

If you are one of the many marine enthusiasts who make regular visits to ogle at the new additions to a dealer's tank, you�ll probably find the strange, unusual and difficult-to-identify fishes most intriguing. It's compelling to want to own a colourful little fish that none of your reeftank-owning mates have tried. But boldly going forth to explore new horizons can have its drawbacks if you don�t research a prospective acquisition.

The Banggai cardinal, Pterapogon kauderni, fell into the category of the unknown and unusual when it was introduced a few years back. Fortunately, this small zooplankton-feeding carnivore turned out to be easy to keep. It feels most secure kept in a small shoal, and en masse they can look very dramatic with their startling black-and-white livery which contrasts beautifully with other more colourful reef fishes.

Banggais are mouthbrooders, the male incubating both the eggs and fry in its mouth, and many hobbyists have bred and raised the young. A favoured method if you run your reeftank using a refugium is to isolate the brooding male in it. There the young are safe from predators, with a plentiful supply of tiny micro-organisms to feed on.

[Ed's note: Although relatively easy to keep and breed in the reef tank, Practical Fishkeeping does not advise that this species be kept due to its conservation status, which is declining due to over-collection.]

Other recommended cardinalfishes include the Pyjama cardinalfish, Sphaeramia nematoptera, the Orange-striped cardinalfish, Apogon cyanosoma, and the Flamefish, Apogon maculatus. These quickly acclimatise to tank conditions and accept most live and frozen foods.

Blennies and gobies

Blennies and gobies are a group where new species keep coming to light. Currently we have to think in terms of the true gobies, Gobiidae; the Dart gobies, Microdesmidae; the dragonets, Callionymidae; the jawfishes, Opistognathidae; and the blennies, Blennidae.

The main true gobies imported include the Lemon goby, Gobiodon citrinus, and Yellow goby, G. okinawae, two brilliantly coloured fish attaining no more than 3cm/ 1.2� in the wild. Both species are easy to keep, but are best kept singly as they are quite territorial. If a pair can be identified, they will live together amicably and spawning may occur.

The Valencienna genus also includes some good reef aquarium subjects, the most recognisable being the Blue-cheek goby, Valencienna strigata, and the Orange-spotted goby, V. puellaris. These attractive gobies are best kept in pairs. They prefer a deep layer of sand or gravel, furnished with small stones or live rock, under which they will make a cave using their mouth.

Deep sandbed filter enthusiasts often recommend these gobies as a means of preventing compaction of the bed, and an active sandbed filter in turn provides the kind of live foods on which they thrive.

Neon gobies

Other recommended members of the true gobies include the Neons, some of which are cleaners - Elactinus genie and E. oceanops being two examples [Ed�s note: These were recently moved from Gobiosoma to this new genus].

E. evelynae, sometimes called the Sharknose goby, and E. illecebrosum are coral-dwelling gobies, often living in groups of 20 individuals or more. Both cleaner and non-cleaner species accept frozen or live foods, but live artemia forms the best diet.

One goby I'd not recommend is the Catalina, Lythrypnus dalli, a vivid crimson with neon blue stripes. Hailing from the Gulf of California, it requires temperatures no higher than 22�C/72�F, and is not a good subject for a reef system.

Dart gobies

The Dart gobies were originally in the family Blennidae, then became members of the true gobies. Now the 30 or more species have their own family, Microdesmidae. The most recognisable species are those from the genus Nemateleotris and include N. magnifica, firefish, and N. decora, Purple firefish. It is difficult to find more startling colour than that displayed by N. magnifica, and once settled into aquarium conditions, it hovers in mid-water, flicking its elongated dorsal fin.

Both demand perfect water, and reef conditions suit them provided you can replicate their natural diet of planktonic crustacea by feeding live artemia two or more times a week.
Dart gobies can be quite territorial if kept as a small group. A pecking order soon develops, with the weakest being harassed and injured one by one until they hide and die, eventually leaving only a pair.

Then there�s Helfrich�s firefish, N. helfrichi, with yellow and magenta on the head and fins (found in pairs in the wild), and some Sleeper gobies such as the Feathertail Sleeper, Oxymetopon cyanoctenosum, and the Spot-tail Sleeper, Ptereleotris evides.

Dragonets

The dragonets, Callionymidae, require no introduction due to two species - the mandarinfish, Synchiropus splendidus, and the Psychedlic fish, S. picturatus. Both are instantly recognisable because of their bold patterns and colour.

These species are not coral reef dwellers in the wild, but live among debris in shallow water in back reef areas. They make good subjects in a quiet tank, especially if well supplied with microorganisms from a refugium and live brineshrimp naupli. Best kept singly or as a pair. Males have a longer dorsal fin and anal fin extensions.

Recommended species include the Ocellated mandarinfish, S. ocellatus, and the Star mandarin-fish, S. stellatus. Both are less colourful than S. splendidus, but more hardy than the popular species. Both are usually sold as Scooter blennies.

Blennies

The final family group is Blennidae. While most species favour the family characteristics - blunt head, elongated body and prominent cirri (small tufts above the eyes) - in terms of behaviour there are often quite different patterns. Some are bottom-dwelling and like to hide in crevices where they usually have an observation post on which they perch, a good example being the Bicolor blenny, Ecsenius bicolor.

The closely related Midas blenny, E. midas, also lives in crannies but is a free-swimming zooplanktivore. The Red lip blenny, Ophioblennius atlanticus, follows yet another behaviour pattern as it lives in tube sponges peering from its home.

You�d easily recognise Petroscirtes species which are free-swimming on the substrate and spend most of their time foraging. These are the real Scooter blennies. Scooters don�t have cirri, but the male has an elongated dorsal used for signalling.

Bottom-dwelling blennies feed on benthic creatures they find on the substrate and browse on algae. Frozen marine foods form a good diet, while those that feed in the water column usually accept frozen, live and flake foods.

Recommended species include the Earspot blenny, Cirripectes auritus; Ornate blenny, Ecsenius pulcher; and Striped scooter blenny, Petroscirtes temmincki.

Keep clear of the False cleaner wrasse, Labroides dimidiatus, which it closely resembles, tearing off flesh and scales. The same applies with any of the Sabretooth blennies, Plagiotremus species.

All the fishes here are small, safe with all types of invertebrates and other fish, and don�t contribute significantly to pollution levels. Reeftank conditions favour them as most will spawn regularly, and a number have been captive-bred.

Jawfishes

A group separately categorised among the gobies and blennies are the jawfishes, Opistognathidae. Identifying the location of these in the fish classification was difficult because of the similarities they have with dottybacks and fairy basslets, Pseudochromidae and Grammatidae.

Most significant were comparable external features such as the pectoral fins, their interrupted lateral line, and the fact that all members of these families are mouthbrooders.

They do, however, have similarities with Dart gobies and true gobies, and some species sport the ocellated dorsal fin markings of the dragonets. It was finally decided they should be categorised as a separate family, but associated with goby and blenny classifications.
Jawfishes are ideal as reef aquarium subjects. They are easy to keep, eagerly accept both frozen foods and live artemia, and make good tankmates for invertebrates.

The Yellow-headed jawfish, Opistognathus aurifrons, is the most commonly imported and prefers a tank with a substrate at least 10cm/4" deep, set among rocks where it will excavate the loose debris to form a cave or a series of caves if you decide to keep a group. Each cave will have only a single occupant, and the fish remain poised at the entrance, ready to move into mid-water to catch prey of free-swimming tiny crustaceans. In the aquarium, frozen or live food can be made to drift by its lair, or use a turkey baster to administer the food.

Other recommended species include Opistognathus rosenblatti, a colourful blue-spotted species from the East Pacific, and Opistognathus scops from the same area, which is sometimes called the Bullseye jawfish because of the prominent eye spot on its dorsal.

This article was first published in the October 2004 issue of Practical Fishkeeping magazine.