So I have had a some fish die recently and noticed a little before death that they seem to not move their left pectoral fins well. Is this a sign of anything specific? It's different types of fish... First was a blue ram a few months ago-died very quickly, within a matter of a couple hours tops, then a Molly about a month or so ago, then a Cory about a week ago, more cories today and I had a bit of panic a little bit ago that my betta was about to suffer the same thing but he is a little perked up now since I moved him to a different tank. I do weekly water changes, test weekly, parameters are almost always spot on. All I'm looking for with this question is a list of possible things/diseases that could cause a left sided issue or a unilateral side issue? I googled and it's not really telling me specifics.