Guppy not eating and isolates himself
I was hoping i could find a bit of help here as one og my guppies stopped eating about a week ago. He's not even remotely interested in food. He doesn't hang around the others like normally and he stays still, near the surface with his tail drooping down. I can't see any external signs of disease on the guppy (called Otto). He can swim down normally if he wants to, but most of the time he doesn't.
We have 3 guppies, 2 mollies and 1 coradora. Others eat and behave normally. We've had the tank for 2 months and one guppy died of swim bladder. This is not swim bladder. It looks different. I'm wondering if it could be internal parasites and what i should do. I cleaned the tank 1.5 weeks ago. Every 2 weeks.
My boyfriend works with small animals and he'll bring some anti-parasite medicine today, but he's not sure it is internal parasites.
Any help would be much appreciated.