Hi I'm new here so any advice would be very much appreciated!
I just got my little halfmoon via post about a week ago, but since then his dorsal fin has been deteriorating. When I got him, the back part of his dorsal was a little mangled, but I attributed that to being in a bag for a few days. However, now the front part of his fin seems to be splitting.
At the same time, though I've had to retank him twice. His first tank was the five gallon Fluval Chi, and everything was going great till I saw him being sucked into the filter (really REALLY upsetting) so I rehomed him into the Fluval view 4 gallon. Now his tail and dorsal fin look mangled and raggedy and are getting worse and I don't know if it's because of his experiences in the horrid Chi or something else.
For reference, as stated previously he's in a four gallon, temps are around 74-75 -- I have a heater but it's been constantly in the 90s for the last month where I live so I don't really think I need to use it for right now. The flow on the filter seems to be a bit much, I created a baffle from another post that seems to be helping, but I might get another tank if things don't get better. I feed him frozen brine shrimp twice a day. In his tank is a little fake plant that I trimmed all the edges that could be harmful off of (but maybe that's causing the damage) and an overturned cup.
nitrate/nitrite: 0 ppm
water hardness: soft/ 75 ppm
chlorine: o ppm
alkalinity: 80 ppm
He's super active, his color is beautiful and he's a little piggie when it comes to food-- so he doesn't seem sick or lethargic or anything.
Is it just damage or is it fin rot?! I'm new to fish and really want to have a healthy, gorgeous betta. Any help would be really, really appreciated.