How to feed upside down catfish that hides

[Tttay89]

I bought an upside down catfish over a week ago for my 110 litre, he was very active in store and very active when I introduced him to the tank and is the largest fish in the tank at around 3.5-4 inches , next day it was gone. I do keep seeing his tail poking out of a cave or from behind drift wood but it's just extremely inactive and uninterested in food (flakes pellets and algea wafers) ..I've even tried putting a wafer inside the cave and wait for him to come and claim it like my albino bristlnose eventually does but nothing....it's been about 8 days and the only time I've seen him swim around is the day I bought him to the point I thought he was too active for my peaceful tank! .. I'm ok that hes a shy fish but I would like him to be fed at least

 

[Byron]

This fish is a shoaling species, which means it must have a small group. It is similar to cories in this respect. So one problem may be fright caused by being alone. If you can get another three or four, all may be well. But do it soon, as the longer the fish is on its own the more stressed it will be and this causes a weakening that then brings on other issues.