I have a 55 gallon grow out tank with some 1.5 inch guianacara, geophagus and satanoperca juvies. On occasion a few of them, not all, will rest on the sand and make snake-like movements for a few minutes and then they snap out of it and act perfectly fine. They all look and act perfectly fine otherwise. I was wondering if this could be a sickness or parasite causing this and if I should treat them for anything. Any advice would be appreciated.