My dad has a pretty 10 gal FW
setup in his office.
He had: 1 gold platy, 1 red-tail black shark, 2 mollies, and a tetra.
Obviously, those fish don't go together well. I bought him the shark, but he went off on his own and talked to people at Petsmart who warned him but didn't prevent him.
When we fed them, there were a lot to eat, but they always all seemed to get what they needed. Today, my dad came home and mentioned he'd noticed a lot of dead fish the night before. I went to the tank and everyone was dead except a mollie, who is lying in a plant and struggling to breathe, and the shark, whose tail is a dull gray now. Definitely looks like swimbladder.
When I pulled out the other three to flush, I noticed that their tail fins, dorsal fins, and (side?) fins seemed shredded. I don't know how long they'd been dead however, because it isn't my tank and I don't typically do the caring for the fish.
I know that swimbladder is a cause of a LOT of things-too much feeding, too little, water chemistry changes, temp change, etc. I also remember reading that bullying was a cause.
Is it possible that the shark was bullying them all and eventually they got swimbladder and died?
The shark seems to be struggling to swim too.
What can I do?
And what do you think happened?