Sickly dojo loach

Hello all this is my first time using this website and I am in desperate need of anything anyone can tell me. I have a 65 gallon, heavily planted (aquatic plants and pothos/swiss cheese plant on top), levels are 7.0~ PH, 0 ammonia, 0 nitrite, around 10-20 nitrate. They are used to much higher nitrate due to old water being naturally high but I'm aware this isn't the best so I have worked diligently to keep it below 20. Unsure of hardness/ect but has never been a issue but can grab if needed. I have a Fluval FX4 pond filter with a spray bar to dilute power on my tank and "clean" it monthly or 2 months via rinsing half off and leaving half fine. My tank mates are adult mollies, platies, glow light tetras, upsidedown catfish, and kuhli loaches with one adult bristlenose pleco. My main tank mate is 3 moderately sized dojo loaches. I plan to upgrade to a 125 gallon once it goes on sale, and have monitored the tank since I am aware it is growing too small for the dojos but they always seem happy, very energetic, well fed with beefheart/brine/bloodworms, vibra bites, cichlid pellets (pre soaked to get rid of air), and fluval color flakes. I do 40% water changes weekly or biweekly based on need. New tank mates would be the glow light tetras but they all look healthy and they are over a week of being new.

Hopefully this is all the information needed.

Today I found my biggest dojo loach, Kale, not coming up for food and was laying in the back. I nudged him and he swam haphazardly away to the front of the tank to which I noticed white stuff on him, not quite fuzzy but not ich. (Assuming now its his slime coat coming off?) I immediately went into panic mode, testing the water (above), checking all other fish (all fine), ect. I did recently have a molly pass but they had been sick for 3 weeks now (skinny clamped type of sick, assuming stress). I had treated my tank for 2 weeks prior with Everything Aquatics trio medicated flakes incase, my loaches have ate this many many times prior as well when they were younger.

He seems swollen on his back end, redness accompanying there plus on his underside and seemingly only one front fin, hes clamped and breathing slow. He is passing gas a LOT but it is clear bubbles, no blood or any discoloration in them. They did not get fed yesterday, but there was a huge thunderstorm and they (all 3) were swimming around as normal, a little erratic due to the weather but normal. Now he swims a bit stiff, and will even just kind of "freeze up" and lay on his side or back. I will include as much pictures as possible.



I set up my 20 gallon tank, fresh water, with aquarium salt for the swelling and prime. He has a bubbler/sponge filter and a fluval filter with a sponge to grow bacteria. I will be dosing prime daily. I have a lot of different medications but was waiting for salt to take effect first. Please please let me know if anyone has a idea od what this could be, what I could do, ect. I have contacted a fish vet as well to gauge prices. These are my babies.

My partner thought possibly a blockage/cannot poop. We ruled out a bunch since it was so sudden seeming, within 24-48 hours. We half ruled out dropsy or such since so sudden but unsure. Thank you for any help.

Hi, I am going to defer to the experts on here but am really interested to learn what it is. I see what you mean with the redness and swelling. I hope he does well.

There's something in the water irritating the fish. It could be ammonia, nitrite, nitrate or incorrect pH. However, your tests would suggest they are ok. In which case it could be chemical contamination from something.

Have you done any water changes lately?
Have you added anything to the tank in the last 2 weeks?
Do you use a moisturising cream or hand sanitiser on your hands?
Do you have buckets and hoses specifically for the fish?

Don't add chemicals unless you know what the problem is and then use the correct medication for the ailment.

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BASIC FIRST AID FOR FISH
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 a week or until the problem is identified. 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 the media. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens so any medication (if needed) will work more effectively on the fish.

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