Surgeons are so-called because of their 'scalpels', the two sharp bony points on either side of the body at the base of the tail fin. The scalpels can give a nasty cut to a clumsy human, but are very rarely used on other fish. Perhaps being wise to the dangers, other fish are not stupid enough to tangle with the surgeons or indeed with the tangs, which also have these weapons.
Tangs and surgeons are magnificent fish, sporting the boldest and brightest markings. They are a good size, they grow steadily, they are relatively hardy, they cause very few problems with other fish and the yare easy to feed. They are safe with tiny and large fish alike, and the yare ideal inhabitants for an invertebrate tank.
It may seem hard to believe that piranhas should be related to the gentle little fishes that make up the majority of the characin group, but it is true. At up to 30cm (12in) long, piranhas are very much larger than tetras, but do not deserve the nasty reputation they have acquired over the years. In the aquarium, at least, the piranha is a relatively shy, retiring creature. Stories of piranhas in the dark Amazonian rainforests reducing cattle to skeletons in minutes are true, but this occurs in a river system where piranhas live in great shoals of 300 fishes or more and become very hungry. Many people keep piranhas with a sort of morbid fascination for what might happen, and give the impression that they would be quite pleased if the fish bit them as evidence of their macho capabilities! Keep young piranhas in a tank at least 120cm (48in) long, but provide a larger aquarium as they grow. Similar in shape to piranhas and also from northern South America, the Pac us can also be kept in a large tank.
Hawk fishes are smallish predators that readily adapt to aquarium life. Most species rarely grow more than 7.5-10crn (3-4in) in length, so as long as they are not housed with tiny fish or smallish shrimps, they can be put with most other available animals. Hawk fishes spend most of their time perched on rocks and ledges watching the world go by - the yare not 'dozy' like lion fishes, for instance, but alert and upright, even though they are stationary. When something takes their interest, whether it be food or a threat, they dart off the rock in a saw like in order to investigate, hence their common name. These excellent community fish never cause problems with other inhabitants; if regularly fed they can live for tn any years in captivity.
The guppy must be one of the best-known tropical aquarium fishes, as well as one of the most beautiful and prolific. It is not aggressive to any degree and can be kept with any other fish that will not be aggressive towards it or grow big enough to eat it. Guppies make no special demands regarding care and will survive in less than perfect conditions(although this is no excuse to neglect them). The guppy originates from Central America and the northern part of South America. In its natural state, it is a relatively uninteresting fish with very little coloration, but over the years, fish breeders have developed various highly coloreds and forms with greatly elaborated fins. This breeding work has been concentrated on the male fishes, which even in the relatively drab wild specimens show more co lour than the females. Depending on the particular aquarium-bred strain, the dorsal fin may either be small or massively flowing, but the male's tail will always be like a long flowing scarf. The tail may he one of several different shapes, depending on the breed, and will also have various names, such as 'delta tail', `velar or`fantail', and so on. The colors of these fish are absolutely stunning.Agai, depending on the particular strain of guppy, it may be red, blue,green, black or any combination of these and any other colors, too.The colors may extend across the body right up to the head. Females
The typical gobby is a small, tube-shaped fish, perhaps about 5-10cm (2-4in) long and often drably colored. It spends most of its life scurrying along the sand. Many gobbies live in small caves or among coral branches and many enjoy a symbiotic relationship with other animals, most notably with certain species of shrimps. Since most gobbies are very hardy and disease-resistant and never cause compatibility problems, the small percentage of brightly species make excellent aquarium inhabitants. They are generally easy to feed on a wide range of readily available foods, including meat foods, dried foods and brine shrimps. These fascinating little fishes are widely available at dealers and not expensive.
Many of the popular tropical aquarium cat fishes originate from South and Central America, Africa and Asia. Most are rather drably colored, mainly because they need good camouflage to avoid predation. As they usually frequent the bottom, the ideal colors are brown and black. Many have poor sight, as they are often nocturnal or live in silt-laden waters. To compensate for this, catfishes have developed barbells, which recovered in taste receptors. Barbells may be long and used for hunting, basin the pummeled or, as in the Cordovans catfishes, short and used to burrow and tease their way into the gravel to detect food or insects. Some catfishes scavenge at the bottom for tasty morsels, others amendatory swimmers that feed mainly on insect larvae. Large predatory species hunt for small live fish, a few feed on fruit and seeds and some of the most bizarre species are parasitic - even to the extent of feeding on other catfishes.
Some of the box fishes are so cute that they simply cannot he ignored they are also known as yellow box fish. These fish are cube or cuboids in shape, and have a hard exterior (though not a retrospection). The hardened skin is only softer around the eyes, mouth and fins, so these fish swim as though in a straightjacket. They are very slow swimmers, though quittance, and settle down well to aquarium life, although they are obviously not adept at battling for food. Smaller species fit well into invertebrate systems.
Of all the tropical aquarium catfishes, Cordovans catfishes must be the most popular. There are many types of Cordovans, a group of very small, well-armored catfishes from South America, with a variety ocular patterns depending on their native habitat. If at all possible, setup the aquarium to simulate the slow-moving rivers of South America,where these catfishes come from. Introduce plenty of plants, somehow and fine gravel to make them feel at home. A tank containing only Cordovans catfishes does not make a very good community, as the fish tend to spend most of the time at the bottom of the tank, leaving the top half looking empty. Cordovans catfishes often take gasps of air from the atmosphere, so do not he alarmed if your fish make a sudden split-second dash from the bottom to the surface; this behavior is totally normal. These busy little beavers are seen in nearly every home community tank and most are easy to keep, although a few can be quite delicate. They prefer their water to be slightly cooler than most theosophical but will quite happily live at the optimum temperature of24°075°F). However, some species need very specific water conditions,especially if they are wild-caught fish, so check before buying.
As a complete contrast to the smallish fish that have been described so far, we come to the giant bat fish. This fish, although often acquired at2.5-7.5cm (1-3in) long, will grow prodigiously, even in an aquarium and very soon reaches 25-30cm (10-12in) in size, being tall rather than long. It is one of the few fish that actually outgrows its immediate environment, and many autarkists are faced with the problem of either buying another tank or part-exchanging their rapidly expanding fish. Bat fish like to 'rule' a tank by swimming unhindered in the open spaces and as long as other fish do not challenge this right of way, bat fish are normally content to live with any other fish, from small gobies up to larger groupers and triggers. However, choosing tank mates can be problem.