kukerdan....
Good purchase!
The Rope (or Reed) Fish,
Erpetoichthys calabaricus, is definitely one of the Polypterids and shares all of their unique characteristics. These primitive fish have ganoid scales (covered with a hard material called ganoine) that are diamond-shaped and that do not overlap....unlike the scales of more 'modern' fish. They have fair eyesight but apparently an excellent sense of smell, probably enhanced by their tubular nostrils.
They have paired 'lungs' which were originally thought to be a modified swim bladder. Some recent thought, however, proposes that many 'early' fish had 'lungs' and that the swim bladder developed from those rather than the other way around. All Polypterids are capable of breathing atmospheric air....and they don't only do it under conditions of low dissolved oxygen in the water. They are also capable of living for quite some time out of the water as long as they manage to keep moist.
The Rope Fish is separated from the genus
Polypterus (the only other living genus) by their much-elongated body and by the absence of ventral fins (which all members of
Polypterus have). In my experience,
E. calabaricus is one of the more 'social' of the Polypterids and they seem to enjoy each other's company.
The only Rope Fish that I personally have right now is in a grow-out tank with small
Polypterus senegalus, Polypterus delhezi and
Polypterus retropinnis. There have not been any incidents of aggression. About 6 weeks ago I made the mistake of putting some medium-sized Yellow-Tailed Congo Tetras into the tank with the bichirs (there are already some good-sized Congo Tetras in the tank) and it was the Rope Fish that made the first strike. Even though the tetra was far too big for the Rope Fish to swallow, it did its level best to kill the tetra and managed to do enough damage that one of the
Polypterus delhezi youngsters was easily able to finish the kill (and swallow the tetra).
Be aware that Rope Fish are not so much jumpers as they are slitherers and will manage to snake their way out of even the smallest of openings. If you have a
HOB filter system...make sure that the opening of the intake tube has one of those mesh covers on it or the Rope Fish might just squirm up the tube and end up in your filter.
Oh....by the way....my Rope Fish enjoys eating bloodworms from my fingertips and will come right to the surface when it is feeding time.
-Joe