I have this platy who seems to be paralyzed from his front fins back. He’s pretty old, I got him from my aunt because all her other fish died except him and a giant pleco. and she was out of town a lot and didn’t notice this guy was having issues (or even alive) so I took him with me. He can’t move his tail at all, still swims around using the front two fins, still eats plenty. He used to just sit at the bottom of the tank and barely move at all except to eat, but I got 2 other platys for him and now he actually swims around (still with only the front fins) and is always like he’s standing upright, has no control at all over his back half. I don’t know what my aunts water conditions were in the old tank. But in the tank I have him in now it’s at 0ammonia, 0nitrites, 10nitrates and about a 7.4 ph. He’s in with my other fish now after being quarantined for a couple weeks. He has definitely improved since I got him but I’m wondering if this is just old age and he’s just less depressed now(he’s about 4 years old I think) or if it’s a disease of some sort. I’ve had him for about 2 weeks. (Just put him in my DT today)