[cdntanks]

Here is what Fishbase.org has on this species:

http://www.fishbase.org/summary/Pollimyrus-isidori.html

Fishbase is a great starting point for a fish you want to learn about.

Also, check out monsterfishkeepers.com they have an informative thread on the various Mormyridae (Elephantfish). Unfortunately, there seems to be some problem with the monsterfishkeepers.com forum server as I post this. I will post the link to the thread once it's back on the air.

 

[cdntanks]

You may want to look into potential internal parasite infestations. There is quite a bit of detailed info here:

http://www.merckmanuals.com/vet/exotic_and_laboratory_animals/fish/parasitic_diseases_of_fish.html

check out Hexamita and Helminth (worm) infections as these may be indicated by the "skinny" appearance. Wild caught fish, like your Mormyidae are commonly infested with internal parasites. There is a great discussion thread on monsterfishkeepers.com but the site has been down for some unknown reason over the past couple of days.

The author of that thread has posted some of the Hexamita treatment details (using Epsom salt) here:

http://www.cyphos.com/forums/showthread.php?t=24515

There has been some discussion that praziquantel is useful for treating worm issues, e.g. Prazipro

If you can get hold of live California Blackworms these should help get him/her eating, but the treatments may kill this live food fairly quickly, so feed sparingly.

Good luck.