Desera calm?

[froguy00]

Sorry for the spelling but I bought a desera about 3 days ago. Today I noticed he was receeding in the middle of his mantal. My maxima is doing fine(I've had him for 5 months) and I dont no whats going on. He's got me worried and I dont know what I should do. Any suggestions.

 

[diddye]

could be flow, parasite, parameters, particles in water etc