Dr. med. Günter Ettrich
Aquarists who have a weakness for keeping predators turn sooner or later to the snakeheads. This family (Channidae), composed of roughly thirty species, is distributed throughout tropical Africa and Southeast Asia. Unfortunately, most of the species are of such a considerable size that only their young are suited to being kept in an aquarium.
I have already tried keeping Channa africana, C. obscura, C. micropeltes, and C. striata. At some point, I always lost interest in the fish and always by the time they reached the size of a good eating trout. For a long time, then, my special interest has been in what is probably the smallest of the species of snakeheads, C. orientalis, which is supposed to grow to only about 8 inches in length. According to Günther Sterba, in many areas of their range especially in mountainous areas - they grow to only 4 to 6 inches.
On Sri Lanka there are two forms of C. orientalis. In addition to the usual form found in Asia, roughly from Pakistan in the west to China and Borneo in the east, there is a form without pelvic fins that is limited to the island of Sri Lanka.
On a trip to Sri Lanka in January 1982, I was able to catch both forms. I was immediately struck by the fish without pelvic fins, which I netted in the southern part of the island. I was absolutely delighted when, after netting for hours in a forest stream that ran relatively fast in places-and coming up with countless Pseudophromenus cupanus, Belontia signata, Aplocheilus, Rasbora vaterifloris, Capoeta titteya, and other barbs, as well as a single small Malpulutta kretseri - suddenly an unusual, beautifully colored snakehead about 4 inches long was squirming around in my net.
The basic color of C. orientalis (the variant without pelvic fins) is brown. In males, depending upon the mood, the flanks sometimes appear dovegray with a violet sheen, becoming lighter toward the abdomen. The male's dorsal and tail fins are sky-blue, black, and orange; the anal fin is blue, bordered in black and white, and the rays of these fins are black. The eye, or rather the iris, is reddish. These are fish, then, that are worth looking at, particularly when they are ready to reproduce. At that time, the females, otherwise more plainly colored, are also quite attractive-appearing primarily in shades of blue. As for size, my fish were quite within the normal range. The largest one was evidently already an old specimen; it was 5 inches long.
Unfortunately, I was only able to get three of the fish home with me (of the original five specimens that I caught, two of the smaller ones were eaten by their companions during the flight home). Fortunately, as it gradually turned out, among them was a good pair, which I put into a wellplanted 65-gallon aquarium. During the first weeks, the male behaved so badly toward his partner that I had to separate them several times so that the female could recover. However, they gradually grew used to each other, until finally they were like an old married couple. It often happened, particularly during the quiet evening hours, that they began circling and embracing near the surface, clearly mock-mating, and I continuously inspected the surface of the water closely. Finally, I learned that snakeheads let their oily eggs float to the surface. At least that is what Armbrust observed in C. africana and C. obscura, and described.
One day, the male fish showed a marked change in behavior: he remained mostly in one corner of the aquarium near the surface. His throat looked slightly swollen, and he refused to take any food at all. When this situation did not change during the days that followed, I decided, fearing some parasite had attacked the animal, to give it a quick medication bath. To my great surprise, when the fish was placed in the bath tank, he released from his mouth two larvae with large yolk sacs, which, evidently because of their high oil content, floated to the surface. Thank heavens the fish kept the rest of the young in his mouth as I put him hastily back into the 65-gallon aquarium!
Going on my personal experience in Thailand and also in Sri Lanka, where I repeatedly found very young snakeheads in very shallow shore zones, I installed in one comer of the aquarium a makeshift shallow water zone made of plexiglas; the bottom was covered with gravel, and I fastened plants above it for cover. Interestingly enough, this shallow-water hideaway was immediately taken over by the brooding father fish.
Eight days after my initial discovery that the male was carrying eggs, I turned on the tank light and observed for the first time a fry that had been released by the father being quickly taken up again into his mouth. The next day, this is how things stood: the brightly .colored male lay quietly in the shallow water zone among the plants, with his head just above the bottom. Beneath his head, a little swarm of dark brown fry about 2/5 inch long swirled around. On the tenth day, I separated the father from the flock of babies as a precautionary measure. As time went by, the eleven baby snakeheads became increasingly a light brown on the dorsal sides of their bodies; finally, they were almost yellow, and in most of them, a black spot appeared on the hind part of the dorsal fin, while the throat and abdomen turned whitish.
They ate Artemia nauplii, small daphnia, and tiny mosquito larvae immediately. As is proverbial for snakeheads, they ate so much you could literally watch them grow. During the first week after the young were released from the father's mouth, they remained to a large extent in a school near the bottom. Not until later did it seem that the accessory respiratory organs ("labyrinth" organs) were functioning. In any event, I did not see them breathing air at the surface regularly until after about a week.
At the end of that same year, I was rearing the third batch of fry. This was the first batch that I left with the parents, which, after the little ones were released from the father's mouth, continued jointly to provide constant care for the offspring. During this time, the female, which was somewhat stronger anyway, took on more of the job of defending the territory. For example, when my hand was poking around the breeding tank, she immediately became enraged and attacked it viciously. However, I have also observed that at the very beginning, the female gathered into her mouth any of the young fry that had gotten lost in the aquarium and took them back to the father again. It was interesting to note that when she did this, she did not spit them out of her mouth, but always (as did the father) released them through the gill openings. Fry raised by the parents visibly grew more quickly and consistently, and with fewer losses. There must have been thirtyfive to forty babies. They caught up with their siblings from the previous spawn, then about three weeks old.
And so it is clear that my weakness for predatory fishes led to the discovery of a new bit of ichthyological knowledge, for, as far as I know, the fact that mouthbrooding snakeheads exist had heretofore not been known.
Related to this discovery, other questions also come to the fore: Is the Channa orientalis that does possess pelvic fins also a mouthbrooder? Is it possible that my C. orientalis (without pelvic fins) is a mouthbrooder only sometimes, under certain habitat conditions, as, for example, is sometimes said to be true for Sphaerichthys osphromenoides, the chocolate gourami? Is it possible that of the snakeheads, only species without pelvic fins, which would include C. asiatica, are mouthbrooders? Are the two Sri Lankan variants of C. orientalis really the same species? (Here, it would be interesting to know, in addition to the mode of reproduction, the size and weight of the eggs in both variants.) Why, on an island as relatively small as Sri Lanka, has there been thus far no hybridization between the two apparently closely related animals? Was, in fact, the original division of snakeheads into the genera Channa (for species without pelvic fins) and Ophicephalus (for animals with pelvic fins) more precise?
These ichthyological questions remain open; perhaps, in the future, interested aquarists will find the answers.
This article was originally published in T.F.H., vol. 37 no. 10, June 1989, pp. 34-36. Thank you Dr. Ettrich for kind permission.