Part eel, part cat...

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The Eel-tailed catfish are rare and quirky, but they’re also charming and beautiful. Steve Grant takes a look a these fabulous oddballs.

There are hundreds of catfishes that are available in the aquarium hobby, but there is one family that only becomes available on rare occasions — the Eel-tailed catfishes, or plotosids of the family Plotosidae. Some of the species are marine, some freshwater, and some can move between the two or into brackish water.

Every now and again, some of the freshwater species appear in retailers, although some are now protected. If you have the room and facilities to keep them, and if they have been legally exported, then they are recommended. But as you will see, care must be taken or you could find yourself in a great deal of pain… or much worse.

Meet the Eel-tails

Reading the clue from the common name, it’s hard to miss the fact that these catfish have an eel-like body. They usually have four pairs of barbels, and there is no adipose fin — this last point is something that’s quite unusual for a catfish. Instead, they have a secondary

dorsal fin that is joined firstly to the caudal fin, and then to the long anal fin in a continuous ‘blade’ around the back. The caudal fin itself can be pointed or bluntly-rounded.

Thankfully from the perspective of correct identification, as they are rarely available, shops will usually know what they have imported and sell them with the correct genus name. The predominantly marine or brackish genera are Plotosus (Lacep de, 1803), from which the family gets its name; Paraplotosus (Bleeker, 1863); Euristhmus (Ogilby, 1899); and Cnidoglanis (Günther, 1864). The freshwater species are Anodontiglanis (Rendahl, 1922); Neosiluroides (Allen & Feinberg, 1998); Neosilurus (Steindachner, 1867); Oloplotosus (Weber, 1913); Porochilus (Weber, 1913); and Tandanus (Mitchell, 1838).

Beyond calling them Eel-tails, other names include Tandan (which is the indigenous name), Cobbler, and Dewfi sh/Jewfish. The two most commonly imported into the UK are Neosilurus and Tandanus. Of these, Neosilurus can be identified by a combination of lack of a dendritic organ (more on that later on); the second dorsal fin originating on posterior (rear) half of the body, frequently near the insertion of the first caudal fin ray; a rounded end (usually) of the caudal fin; and the dorsal profile of the head being straight or convex and the front nostrils being situated on the end of the snout and pointing outwards or upwards.

 

Read the rest of the feature in the February 2022 issue. Buy the latest digital edition and read instantly on your computer, mobile or tablet device.


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