Hello I have what I believe to be a constipated Pleco. There have been no poos for a long time (7days+) and he won’t eat. I’ve tried offering peas and courgettes to help but he won’t touch them. I’ve been dosing the water with melafix in case he has something. I’ve tested the water and it’s ok/nothing’s changed. We have a little an algae problem so I’m planning on emptying the tank but had to wait until the Melafix course was finished (tomorrow) and was trying not to stress him but I’ve run out of options. He is probably now just about reaching too big for the tank (240L) and I know I have to rehome him but can’t while he’s sick. All remedies I’ve read seem to involve him eating stuff but he won’t eat.
Garlic is generally considered a good appetite-stimulant for fish - it might be worth soaking the peas or courgettes in some garlic juice or else trying fish food already containing garlic. Another option is the Repashy products - ordinarily, I might have suggested Soilent Green, but I've recently heard very favourable reports about its Morning Wood product for plecs.
Having water at optimum quality is also crucial - so, if there is any presence of ammonia or nitrite, then it'll be crucial to eliminate that and ensure water quality is at 0 ppm for each, and no more than 20 ppm above tap water levels for nitrates. It might be that small, daily water changes perk him up a bit, even if the water quality seems optimum.