Article © Shane Linder, uploaded January 01, 2002.
The members of the family Chacidae epitomize what it means to be a catfish hobbyist. Cichlidophiles and killiefish specialists are always on the hunt for new brightly colored and beautiful acquisitions. But, only the catfish hobbyist would actually seek out and pay good money for what has to be the ugliest family of freshwater fishes. How do you describe a chacid? Well, imagine a fat ugly banjo catfish (aspredinid) that can swallow prey up to half of its own length in a single gulp! Yes, this is absolutely a fish that only a catfish person could love. To quote Ginny Eckstein, "They're so ugly, they're cute."
The family Chacidae consists of only the single genus Chaca. There are currently three recognized species that belong to Chaca. These are Chaca chaca (Hamilton, 1822), C. bankanensis (Bleeker, 1852), and C. burmensis. If C. burmensis is new to you, that is because it was "only" described in 1988 by Brown and Ferraris.
The geographical distribution of the family is quite interesting. Chaca chaca is found in the Ganges-Brahmaputra drainage of India and Bangladesh. Moving east to the Sittang River in Burma, we encounter C. burmensis. Roberts included the Irrawaddy basin in Burma as part of C. chaca's range, but with the addition of C. burmensis to the family, it seems very likely that the Chaca species Roberts recorded was actually C. burmensis. Finally, C. bankanensis is found only in the southernmost region of Southeast Asia (southern Thailand, Malaysia, Sumatra, and Borneo).
There is a gap in the family's distribution. No chacids are found on the northern Malay Peninsula. C. bankanensis is thus separated by some distance from the other members of the family. As one would expect, C. chaca and C. burmensis are more closely related than either species is to C. bankanensis. However, it appears that C. burmensis does share some features with C. banknensis that are absent in C. chaca. The distribution of Chaca is a fantastic insight into how a single genus, descended from a common ancestor, evolved as it spread across southern Asia.
The close relationship between C. chaca and C. burmensis makes it nearly impossible for the hobbyist to distinguish the two species. The majority of differences are osteological (i.e. based on bone structures). C. bankanensis is also difficult to distinguish from its congeners. One difference Roberts noted was that C. chaca had five pectoral-fin rays and C. bankanensis four. However, Brown and Ferraris list C. burmensis as having 4-5 pectoral-fin rays. Thus, one of the few external differences that hobbyists used to rely on to tell the species of Chaca apart, is no longer useful. Most shipments of Asian tropical fish bound for the hobby originate in Southeast Asia, so it is no surprise that the vast majority of Chaca imported are C. bankanensis
C. bankanensis is found only in the rainforests of its range. These fish are often caught in peat swamp forests. In these blackwater environments the water is acidic (pH 3-4) and soft. The water is as dark as coffee and slow moving. One can imagine a C. bankanensis, so perfectly camouflaged, laying in wait for some prey to chance by. Such waters are also very low in bacteria and this would explain why C. bankanensis seem "prone" to infections. Carefully inspect any Chaca before purchase to ensure that you buy only healthy specimens. Since Chaca are not active fish, buyers often assume the lethargy to be natural and not a sign that something is wrong. Ask the salesperson to feed the fish while you watch. This is the best way to observe the health of these fishes.
All Chaca are strict carnivores that will eat only live feeder fish. Take this into account when you purchase them. They also must be kept in a species tank. Ginny Eckstein reported that feeder guppies that are not eaten are usually found dead. It is possible that C. bankanensis is capable of releasing a toxic substance. This theory is given further credibility by the fact that natives in Sumatra consider the flesh poisonous. It has yet to be seen if C. chaca or C. burmensis are capable of releasing a toxic substance. Neither species is reported as poisonous and C. chaca has been maintained in community tanks.
The "accepted" feeding habits of this fish are also disputable. Chacidae are referred to as the "angler-catfishes". This name comes from the theory that they lie in wait and move their maxillary barbels in such a way as to resemble a small worm. When a passing fish is attracted to the false worm, it is swallowed whole by the Chaca. Hobbyists have noted that this behavior is not observed in the aquarium. It is true that, like all catfishes, Chaca move their maxillary barbels. But, are they really trying to imitate a worm? How useful would this technique be in C. bankanensis' habitat where the water is as dark as coffee? It seems more likely that Chaca use their fantastic camouflage to ambush and engulf their prey. The question of whether or not Chaca "angle" deserves further research.
C. chaca has been spawned in the aquarium. Four Chaca were kept in a 36" X 18" X 18" tank. They were fed on a diet of tubifex, shrimp, small fishes, earthworms, and chopped beef heart. Nandus (leaf fish), Danios, and Rasboras were also kept in the tank. The tank had no substrate, but held a piece of driftwood and a pipe (8" long 3" diameter and made of asbestos!). The breeding tank was not heated, but the ambient temperature ranged from 80-95F during the day. The water had a pH of 7.5 and 4 DH. The eggs were guarded by one fish in the pipe (sex unknown) until they hatched three days later. Many eggs fungused, but even so, up to 392 Chaca were raised from a single spawn. The fry grew well on a diet of brine shrimp nauplii and daphnia.
The care of C. bankanensis is relatively simple. The ideal species tank would have a large bottom area covered with boiled oak leaves, a few pieces of driftwood, and spawning pipes. Provide gentle filtration, preferably with peat, and clean soft acidic water. A reliable source of disease free feeder fish would also have to be found. Given such conditions, it may be possible to entice the fish to spawn.
There can be no doubt that the chacids are for the specialist. They are truly a catfish fancier's catfish. Enough mystery remains of their feeding, social, and spawning habits to make devoting a tank to them worthwhile. The catfish hobbyist that looks beyond the physical appearance of the chacids will find them a fantastic addition to any collection. Besides, what other catfish symbolizes so well the ability of a catfish hobbyist to find the bizarre attractive? In fact, I have often thought that the North American Catfish Societies mascot should be a Chaca!
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