While catfish are ubiquitous in the freshwater hobby, they are very few that are available to the marine aquarist. This is due to the fact that there are not nearly as many catfish that live in seawater, especially around tropical coral reefs. Plotosus lineatus, the coral catfish, or striped eel catfish, is the only saltwater catfish species regularly encountered in local fish stores; in fact, it is quite common. Potential coral catfish owners should be aware that this fish packs a venomous wallop! The toxin that is injected through the fin spines can be as virulent as that delivered by the more notorious scorpionfish (it hurts like heck if you get stung!).
Difficulty: The long-term care of Plotosus lineatusis not difficult. Note that the cute, boldly marked juvenile coral catfish sold at your local fish store become 1-foot long, dull brown catfish that have less aesthetic appeal than the channel catfish you might pull from a local lake. The coral catfish rarely succumbs to parasites or disease, and it will also eat almost anything offered by the hobbyist (like all your marine pets, you should provide as varied a diet as possible, including frozen marine preparations).
Physical description: As juveniles, the coral catfish exhibits a striking color pattern consisting of a dark brown background on the back and the sides. Along with a white belly, there are white pin-stripes from the tip of the snout to the tail, and they also have white whiskers. As the coral catfish grows, the stripes become thicker, and the brown becomes a drab mud tone. In all sizes, the dorsal and anal fins merge with the tail — they are more like a pollywog in form than a “normal” fish, and they move like the amphibian larval stage, as well (they undulate most of the body as they swim).
Range: The coral catfish is wide-ranging in the Indo-Pacific, from the Red Sea and Eastern Africa to Samoa. The coral catfish tends to prefer coastal reef habitats, and adults are occasionally found in estuarine conditions. While Plotosus lineatus is common in very shallow water (especially the juveniles), the coral catfish can be found as deep as 100 feet of water.
Compatibility: The coral catfish is a very gregarious fish. In the wild, young fish are most often found in large schools (that can number in the hundreds) that “roll” along the bottom. The leading edge of the school will descend to the bottom and stop to feed in the sand or mud with their barbels. When the coral catfish stops feeding and ascends back into the water column, the fish just behind them will take their place foraging on the sea floor. This continues until all individuals in the group have had a chance to feed, at which time the school moves on. In the aquarium, juvenile coral catfish do best when housed in groups (try five or more). But as mentioned above, Plotosus lineatus can grow to over 12 inches in length — what are you going to do with 5 feet of catfish? The adult coral catfish are not nearly as social or showy as the juveniles. The coral catfish spends most of the daylight hours hiding, usually by itself, under aquarium decor. The adult coral catfish are also highly predatory and will eat ornamental crustaceans and any fish that they can catch and swallow whole (they are most likely to “knock off” fish tankmates at night as their victims sleep).
Aquarium conditions: The coral catfish should be kept in an aquarium with a sand bed (it does not have to be that deep — say a couple of inches of substrate) and some suitable places to hide. Remember, while juveniles will remain in the open if they are kept in groups, the adult coral catfish are more secretive and will need a good “hidey hole.” The following parameters are optimal for your coral catfish: pH of 8.1 to 8.4, specific gravity of 1.019 to 1.025 and a water temperature of 72 to 82 degrees Fahrenheit.
Care considerations: The coral catfish are awesome scavengers, grubbing about around the live rock, in cracksand crevices, and in the upper layers of the sand bed for uneaten morsels. The coral catfish use their barbels to taste the amino acids present in the meaty foods that they prefer.
Breeding: While the coral catfish has been bred in large ponds, it is not likely to spawn in the home aquarium.