Glass cat fish problem

[Eudgoasu]

I have 2 glass cat fish in a 20G. For 2 weeks they stayed in the upper right corner of the tank. The tank is crowded but they didn't seem to be upset. They ate well, only frozen brine shrimp (http://www.fishlore.com/brine-shrimphatching.htm), chasing it. There is no agression in the tank. But now they discovered the cave. All day long they swimm in the cave, holding spot like only glass cat fish can do. One is comming out for food. The other one is the problem. It won't come out. It's for a week already. That one is eating in the cave because the water current get food in there. If I take the cave out or change position that fish will find it again and hide in it. Should I worry ? The fish, as much as I can see it, doesn't look sick. Is it stressed by the environment ? How come the other one is bold ?
Advice, please.

[trev68]

You shouldn't worry too much. The brilliant thing about glass cats is when they are very stressed they turn opaque. It will be the personality and natural wariness of the fish.
Having said that glass cats are a schooling fish and usual reccomendations are to have about 5 together