The rare and remarkable red-eye pufferfish

The red-eye puffers are a quartet of species that are only rarely traded but are eagerly sought out by discerning aquarists. One species, Carinotetraodon lorteti, has been kept infrequently by aquarists for decades, but the three other species, Carinotetraodon irrubesco, Carinotetraodon salivator, and Carinotetraodon borneensis, are very rarely traded. Carinotetraodon salivator in particular has become almost legendary in its rarity, being much talked about by aquarists but almost never seen outside of aquarium books. Nonetheless, enterprising retailers have started to bring in these fishes with a bit more frequency, so hopefully more aquarists will be able to try out these wonderfully appealing little fishes.

Part of the attraction of these fishes are their brilliant colours; these are the Apistogramma of the pufferfish world. In breeding condition, male Carinotetraodon salivator, for example, sport a dazzling pattern of brown and yellow stripes across the head and body, topped off with a bright red eyes and tail. Male Carinotetraodon lorteti, on the other hand, has thick yellow bands squiggling across its back and a blue tail edged with white. The males of all species flaunt an orange or red ventral keel when threatening one another or trying to impress a female. It's a shame that these colours are so mood dependent, because in the overcrowded and brightly lit environment of a retailer's tank, these pufferfish won't look their best. But get them home and settled in, and you'll quickly see why these fish are in such demand!

Historically, pufferfish keepers have not been well served with aquarium books, with much information being either erroneous or incomplete. The single best book on the market is undoubtedly Aqualog - The Puffers of fresh and brackish waters,, written by an experienced pufferfish collector and keeper, and an essential purchase for anyone interested in these animals. Besides describing all the species traded as aquarium fish, there is detailed information on healthcare, diet, social behaviour, and breeding.

Aquarium husbandry

In terms of basic care, red-eye pufferfish should be thought of as fishes for the single species aquarium. Because they are quite small (around 5 cm in length) this isn't difficult to accommodate, and a 20 gallon aquarium will make a good home for a pair of these fishes. The two sexes are strongly dimorphic, with the males being larger and brightly coloured, whereas the females are generally mottled brown with a light underbelly. Both sexes sport the bright red eyes that give these fishes their common name and immediately distinguish them from other dwarf puffers.

As with most other Southeast Asian freshwater fish, these puffers prefer warm, soft, slightly acidic water but will adapt to harder water readily enough. Water quality does need to be very high though, and as with pufferfish generally, they have little tolerance of nitrite or ammonium. In fact, try to keep even the nitrates as low as possible. Avoiding overfeeding, perform frequent water changes (at least 25% per week), and use nitrate-removing chemical media if your filter has space for it.

These fishes are easy to feed, and will take most small invertebrates such as frozen bloodworms and krill. Unlike some of the larger pufferfish, the red-eye puffers don't seem to have the same problems with overgrown teeth, but the addition of a few pond snails and other crunchy foods is probably a good idea nonetheless. Red-eye puffers are, if not entirely nocturnal, then certainly crepuscular. When newly imported, they are most effectively fed early in the morning or late at night. Once settled in, they will learn to recognise their keeper, and will be much easier to feed during the day.

Social behaviour and breeding

Red-eye puffers can be fairly described as territorial fishes that do not mix well with other species. The arguable exception is Carinotetraodon irrubesco, but even then, there are slightly too many stories of fin-nipping or waspish behaviour to make these normally mild puffers classifiable as community fish. In short, these puffers are all best kept in their own tank. Among their own kind, pairs often work well, provided the tank is big enough for both fish. Line-of-sight is very important for puffers, and if one fish can't see another fish, then both fish will likely coexist amicably. So any aquarium designed for a pair of red-eye puffers needs to have lots of plants (real or plastic) and several suitable caves, so that any harassed fish has a place to hide away, out of sight. Red-eye puffers are also fairly retiring animals, so the plants will give them a sense of security as well, and only when properly settled in will you see them swimming about in the open. In suitably large aquaria, it is possibly to keep either multiple specimens of a single species, or pairs of two or more different species. Allow each fish 5-10 gallons of space, and try to ensure females outnumber males if you want to minimise aggression.

Carinotetraodon lorteti is the only species that is regularly spawned in aquaria, but the other species can be assumed to be breedable in the same way. The pair court for some time, with the male flaunting his colours and raising his dorsal and ventral keels. Eggs and sperm are shed onto the substrate, usually something like Java moss. The female is then driven away and the male assumes sole guardianship of the spawn (the female is perhaps best removed at this point for her own safety). The eggs hatch after about 3 days, and the tiny fry remain in the nest using up the last of their yolk supply for another two days. Once free swimming, the fry will accept tiny live foods, primarily infusoria and Cyclops nauplii.

Carinotetraodon lorteti

This is the "standard" red-eye pufferfish and the one most commonly traded. Males are brownish above and cream-coloured below. Running across the head from eye to eye are two yellow bands, and additional bands run from the pectoral fin diagonally upwards to a spot between the dorsal fin and the base of the tail. The tail is greenish-blue and edged with white, while the anal and dorsal fins are usually reddish in hue. Females are smaller, mottled brown above, and almost uniformly cream-coloured below. Carinotetraodon lorteti is among the more aggressive of the red-eye puffers and only limited success has been had keeping this fish in community tanks.

Carinotetraodon irrubesco

Known as the red-tailed red-eye pufferfish, this species is similar to the preceding one but both sexes have red tails. Instead of yellow bands, the males have light brown to cream-coloured bands. Female Carinotetraodon irrubesco are very similar to female Carinotetraodon lorteti, but instead of being uniformly cream-coloured, the undersides of these fish bear short, squiggly brown markings. Carinotetraodon irrubesco are usually shy and fairly easy-going fish, and have been kept successfully in community tanks with fast-moving species such as tetras. Even so, some specimens do become confirmed fin-nippers or simply outright aggressive, so adding these to a community tank is chancy. They do mix well with South American puffers though, the two species entirely ignoring one another. Red-tailed red-eye puffers have been bred in aquaria, though infrequently.

Carinotetraodon salivator

Known as the striped red-eye puffer, males of this species are most similar to male Carinotetraodon lorteti, but when in breeding condition the flanks, dorsal surface, and entire head region are marked with zebra-like light and dark brown stripes. Outside of breeding condition these stripes are far less vivid, but they should still be easily discernible. Females can identified easily by the continuous longitudinal bands running along the belly from the throat to the base of the tail; while female Carinotetraodon irrubesco also have markings on their bellies, in that species the markings are irregular spots and squiggles. All in all, an exceptional species, but sadly as good as never traded. An aquarist lucky enough to obtain some of these fish should certainly consider trying to spawn them, as this has not yet been accomplished in an aquarium. Said to be fairly aggressive in aquaria and a fin-nipper.

Carinotetraodon borneensis

Almost never traded, the Bornean red-eye puffer is very similar to Carinotetraodon lorteti, though confined to Borneo, whereas Carinotetraodon lorteti is known from Cambodia, Laos, Malaysia, Thailand, and Vietnam. The chief morphological difference is in the colour of the anal fin, which is reddish on Carinotetraodon lorteti, but colourless on Carinotetraodon borneensis. Since this fish is so rarely traded, not much is known about its behaviour in captivity, though maintenance is likely to be similar to Carinotetraodon lorteti.

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