Marbled Talking Catfish Sick After Pictus Dying Fast

A few days ago, I found 2 of my 6 Pictus Catfish alive but belly up, breathing fast, and not being able to move. I removed them to a quarantine tank immediately and noticed a slight film on the rest of the pictus catfish. I removed 3 that I could find to the quarantine tank and did a water change. When I did a water change, I found the last pictus, which was dead and caught in a part of the tank I couldnt really see. He didn't have any diseases that I could see. The rest of the pictus died within a day. The remaining fish are 6 ghost catfish, all who seem healthy and unaffected, and my marbled talking catfish, who seemed fine but has been getting worse. His eyes looked slightly clouded, maybe even scratched, but he has been burrowing in the sand, so I wasn't sure it it was that. Now, his eyes are fully clouded and white, he has a red spot on his pectoral fin, and there is some red on his back fin. His back fin has recently been receding. He has a little bit of film on him as seen in the pictures.

Tank parameters: 55 gallon with 6 glass catfish (3 inches), 1 talking marbled catfish(3.5 inches), and 6 (now removed) pictus catfish (3 inches)
Ammonia is 0, nitrite 0, low nitrates, sandy bottom with two wood pieces and a decent amount of silk/fake plants.

The pictus are the newest to the tank, added 1 month ago. I originally got 4 and they were fighting for territory and I read online that they could fight in low numbers/for the first week being new. I added 2 more to bring the shoal to 6. They got a lot better. All barbels bitten in the first week grew back and they could lie together and be fine. For the past week, they had been swimming towards the top of the tank, which I thought meant they were playing, but now I read that they were stressed.
My biggest concern now is my Marbled Talking Catfish. I've had him a long time and I have been through alot with him and am terrified I'll lose him. I've done extensive water changes and have put Melafix and Pimafix in the tank to hopefully help if it's bacterial/fungal. I've heard of pictus accidentally poisoning fish and he likes to sleep vertically against the glass and a pictus could have swam up and scratched and poisoned him. Any help is appreciated!!

All very sad. I am new. I hope the smart people here know.

Cloudy eyes and excess mucous on the body and fins indicates something in the water irritating the fish.

Red on the tail and fins is usually bacterial, but the bacteria get in because of damage to the tissue caused by an injury or poor water quality damaging the skin.

If the last fish added were the pictus catfish one month ago, it is unlikely to be a disease like a protozoan infection.

I would say it is a water quality problem or chemicals in the tank.

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Wipe the inside of the glass down with a clean fish sponge. This removes the biofilm on the glass and the biofilm will contain lots of harmful bacteria, fungus, protozoans and various other microscopic life forms.

Do a 75% water change and gravel clean the substrate every day for one week. The water changes and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use them. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens.

Increase surface turbulence/ aeration to maximise the dissolved oxygen in the water.

If there's no improvement after a couple of big water changes, post more pictures of all the fish.

What is the pH of your tank

itiwhetu said:

What is the pH of your tank

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6.6

PicassoTheCatfish said:

6.6

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perfect for these guys, so something else is going on. Can you post a picture of the whole tank? That might show something.

itiwhetu said:

perfect for these guys, so something else is going on. Can you post a picture of the whole tank? That might show something.

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Biofilm/algae bloom but no ammonia or nitrites. I had it in my other tank and it went away/my pleco ate it. There are balls of white stuff on different things. The water used for this tank is the exact same as in my other tank and my other tank has all healthy fish. My catfish does have some scratches on closer to the back fin on his right side.