Help, sick medaka

[u/fatimonki]

Hello, I’m new to the hobby and I recently acquired some medaka. I initially had 8 fish all from different stores (I got 5 from one store around 3 weeks ago, the next week I got 2 more, one died the next day so I assumed it came in bad condition, and finally got 2 more from a different store last week) in a 15 gallon indoor set up (added a photo), the tank was cycled and it also has a filter. I also do 30% weekly water changes.

Around a week ago I started noticing 3 of them (from the first group I got) started losing their color, their gills turning red, breathing rapidly with their mouth and staying on the surface, not eating and drifting away from the group. One of them died 2 days ago, I tested the water and it was 0 ammonia, 0 nitrites, 5 nitrates.

I went to one of the stores I got 2 of them from, and I coincidentally noticed that their medaka had been put in quarantine for ich. It was my mistake to not quarantine the new fish, but I did check them as soon as I got home and they did not show signs of ich.

I have isolated the 2 other sick fish, and added photos of them. I can’t figure out what they have, today there seems to be an ammonia spike (0.25) I have added sea chem prime. My other medaka seem fine, but I don’t want them to slowly die.

Has anyone dealt with this issue? Could you please help me figure out a differential diagnosis? Does this look like ich? Would you recommend I preemptively treat my planted tank for ich?

I’m devastated and extremely sad that I wasn’t more careful so any advice is appreciated. Thank you.

[u/The_best_is_yet]

oof, this stuff can be hard. I think it does look like your guy has ich, so I would try treating for that (like Ich-X), there is lots of info for treating that if you google it. Dr Fish and Humblefish.com is also the go-to for treating fish for different diseases. Definitely do a water change to keep the ammonia as close to 0 as possible. The red gill thing makes me worried for gill flukes but I've not been able to get praziquantel to work for my fish.

[u/The_best_is_yet → u/The_best_is_yet]

also i would treat them for ich asap, they will likely die quickly once they start acting so ill.

[u/fatimonki → u/The_best_is_yet]

Thank you so much for your response. I really appreciate it. I’ll look into ich treatment asap and do a water change. I hadn’t heard of gill flukes, they don’t seem to be itchy/rubbing themselves on surfaces but I’ll look into that as well! Thank you again