Persistent Fin Rot- Help!

[RKehrer94]

1~The issue: I have 2 female betta fish that have been showing signs of fin rot for about 3 weeks. One of them (green) seems like the edges of her fins are going translucent, whereas the other one (blue) has really ragged fins that are turning red. They had another tank mate that had been in a hospital tank for about 2 weeks with what seemed to be a swim bladder issue, so I suspect the same bacteria was what caused both issues. I’ve been treating the tank with increasing amounts of aquarium salt (currently 4 tsp in 8 gallons), but it doesn’t seem to be having an effect.
2~Tank parameters: Ammonia 0, nitrates 0, nitrites 0, pH 8, temp 26C
3~ Tank history- the tank is 35 L and has been set up for 9 months.
4~Filtration: I’m using a Aquael ASAP 500 filter.
5~ Tank Mates: There are 2 betta fish, at approximately 2 cm long each.
6~Cleaning: I did a water change and vacuum today. I do this once a week, and I’ve been doing 50% water changes since I saw the fin rot develop. Before that, I would do about a 20% change.
7~ I have had the fish for 9 months.
8~ The only new thing about the tank was moving the 3rd betta to the hospital tank, but that was after she started looking worse for wear (and then noticed the present ones were developing fin rot), and that was 2 weeks ago.
9~ Food: I feed them about 5 betta pellets morning and night. There have been no diet changes.

 

[Andy Sager]

Persistent fin damage is usually a sign of improper diet or vitamin deficiency. I'd either feed the fish more than just pelleted foods or add liquid vitamins to the tank and food. I'd also keep up with more frequent water changes if you are only doing 20% at each change. I'm assuming that the divider I see in the tank has been there before the fin damage occurred or else the damage could also be from each other biting each other. Just because they are females does not mean they won't fight with each other.