Compared with the typical "freshwater" puffers the dog faced puffer is rather plain. It is basically a grey-brown in colour, but with attractive stripes and spots. These puffers are fast growing, and able to reach a size of 15 to 20 cms (6 to 8 inches) in captivity. Like other puffers they feed mostly on small crustaceans and molluscs. This precludes keeping them with invertebrates.
A distinct adavatage of these puffers is that they are very hardy and peaceful. Although territorial, they ignore other species of fish, and so can be combined with other robust fish. Ideal companions would include monos (Monodactylus), scats (Scatophagus), and shark catfish Arius, which all enjoy similar conditions.
They are usually imorted as marine fish. While they will adapt well to a brackish water aquarium it is important to allow the fish to adapt to the new conditions. Although it can survive for short periods in freshwater it is best to keep Arothron hispidus in fairly salty conditions. A specific gravity of around 1.010 and upwards would be ideal. Use plenty of calcarous material in the filter since this fish appreciates a high pH and very hard water. Also make sure the water is very oxygenated. Marine fish differ from freshwater fish in being less tolerant of low oxygen levels in the water.
The best way to adapt Arothron hispidus, or any other marine fish, to an aquarium of reduced salinity is to slowly introduce low salinity water to the fish over a period of hours. Ideally, set up a small holding aquarium with marine-strength sea water, and keep the new fish quarantined in there for a day or two until it feeds happily. Loss of appatite is one of the best indicators of an unhappy fish. Then, over the course of a few hours drop he salinity by changing some of the quarantine tank's water with some from the brackish water aquarium. Once the two tanks have the same specific gravity, the puffer can be moved safely.
If you don't have a second tank, consider setting the main brackish water aquarium up at full strength sea water at the start. Then introduce any marine fish and let them settle in. Once this is done and you want to stock with brackish water fish, reduce the salinity of the tank by making partial water changes with low salinity water.
Batfishes are large, friendly fishes that can only be kept in big aquaria. They do well with any other peaceful fish, but since they are quite active do not mix them with very timid fish, which are likely to be bothered by them. On the other hand, peaceful schooloing fish like Monodactylus are ideal companions.
There are three species imported. All are rather similar as adults, being rounded and silvery brown. They are most easily identified when the fish are young.
Platax teira
Known as the long finned batfish. Juveniles look very much like freshwater angelfish, but are rather darker. The dorsal and anal fins are very long, and the pectoral fins are elongate as well. In colour they are a rather murky brown.
Platax orbicularis
The round batfish batfish resembles the long finned batfish, but the juveniles are rather more rounded and leaf-like.Platax pinnatus
Perhaps the prettiest batfish, known as the red-stripe or red rimmed batfish. The juveniles are similar in shape to the long finned batfish, but are much darker brown, almost black. The fins have a red or orange edges, and the face has some markings as well. It is a distinctly predatory fish, and even when small stealthily creeps up on small prey items. The other species are less predatory and adapt to dead foods more easily.
All three batfishes grow from 90 to 100 cms (20 to 36 inches). They are also notable in reaching large sizes irrespective of the size of the aquarium. For this reason, do not by a small fish hoping it will grow to the tank. It won't.
Like most snappers a highly predatory fish. In addition it grows big, to 100 cms (39 inches). Basically not an aquarium fish.
According to "Damselfishes of the world" by G R Allen (Mergus: Melle, Germany) there are three damselfishes that live in coastal freshwater streams and estuaries. These are Stegastes otophorus, Pomacentrus taeniometopon and Neopomacentrus taeniurus. A fourth genus Dischistodus is restricted to silty, coastal waters.
Stegastes otophorus is from the Caribbean and Panamanian coast. The salinity range is quoted as 3 to 31.5 ppt (i.e, about one-tenth to full strength marine). The photographs show a pretty fish, with a rounded shape rather like a seargent major. The overall colour is initially a grey-brown, seemingly getting a deeper chocolate with age. The dorsal, anal and caudal fins have very attractive bright yellow edges. The juvenile seems to have a row of small blue spots along the back, and the yellow markings are not so bold. Maximum size is quoted at about 10 cms. In all, these seems a very desirable fish. Sometimes called the freshwater gregory.
Pomacentrus taeniometopon is from the western Pacific and Indo Malaya. It is said to occur in freshwater occasionally, brackish lagoons and shallow reefs with freshwater run-off. The juvenile is pretty, with a orange base to the caudal fin, a black and white eye-spot at the end of the dorsal, and some blue markings along the head and back. The lower parts are pale pink, darkening along th sides to a grey-blue. The adult is blue-black all over, with no other markings save some blue scribbles along the forehead. Rather like the Neoglyphidiodon (Abudefduf) oxyodon. It may sometimes be imported under that name. It differs from Neoglyphidiodon (Abudefduf) oxyodon (which is known as the black neon damsel) in not having the white, saddle-like band. Slightly smaller than the Stegastes otophorus.
Neopomacentrus taeniurus is widely distributed from East Africa to Australia. Appears to be an inhabitant of brackish rather than pure freshwater. This fish has been seen kept the fish in freshwater, according to the dealer, for some months. The fish looked healthy enough but was very skittish. Possibly because it was the only specimen in the tank (with angels and Corydoras); but it may also have needed a 'taste' of salt to be really happy. In appearance similar to Stegastes otophorus but with more tapering fins and a more 'chromis' like shape. The edges of the caudal fins are also dark in colour. Neopomacentrus taeniurus is known as the freshwater demoiselle.
"Salt-water Aquarium Fishes" by Axelrod and Vorderwinkler (TFH: Jersey City, USA) includes this species (as Pomacentrus taeniurus). It gives a description largely matching Allen's above, but adds that the upper half is purple and the lower half is olive. This would appear to be a description of a juvenile, changing colours when mature like Pomacentrus taeniometopon and many other damsels.
Some other damsels seem to adjust to low salinity marine aquaria, for example humbugs and seargent majors. They are routinely kept around 1.018 by marine aquarists. Abudefduf saxatilis has occurs in many different coastal waters and may adapt to less, but shouldn't be kept in water of specific gravity much below 1.015, i.e. half strength sea water.
The 'freshwater damsels' are rarely imported deliberately, but may turn up as oddballs or in mixtures. They can be considered hardy and worthwhile. Typically, damsels enjoy frozen and dried foods. Some damsels are breedable, and these are worth a crack at. Raising marine damsels is tricky because the young are small and somewhat planktonic. Riverine or estuarine species might be different, and perhaps easier.
All damsels are territorial, although the degree of aggressiveness varies. I would mix these fish with small open-water fish like livebearers or rainbows rather than with dwarf cichlids. Allen suggests Stegastes (as a genus) is best kept alone or in pairs; Neopomacentrus as small groups; and Pomacentrus alone or in pairs. This applies to the fishes behaviour toward other damselfish. Different looking fishes tend to be ignored, but cichlids might be too similar in shape and behaviour and might end up fighting.
Plotosus lineatus are usually imported as juveniles. The attractively striped youngsters are peaceful shoaling fishes, and should be kept in groups. As they mature they become less gregarious, and the adults are solitary. In addition it grows big, to as much as 100 cms (39 inches) in the wild. Plotosus lineatus possesses venomous fin spines. In strength the venom is more painful and dangerous than Arius. Large adults may deliver a sufficiently large dose to cause serious harm.
Although the juveniles are basically marine, the adults can be found in brackish waters and very rarely freshwater. Keep the juveniles in aquaria with well filtered marine strength seawater (specific gravity over 1.018). The adults should be kept alone but can be mixed with different fish such as scats. A specific gravity of 1.010 upwards is needed for long term health. The combination of space requirements and venomous nature mean that this is really not a good aquarium fish.