Backyard Aquaponics
A place to discuss aquaponics

Looks like fungal, increase salt to 3ppt (3 grams per L of water). However, 25 catfish in a barrel sounds like a lot, how much filtration do you have?

Thanks for the feedback... and Mel Redcap too

I just checked the levels with the API chem.kit (as opposed to strips), and they are as follows:
Am 0 ppm
No3 0 pmm
No2 0 ppm
pH 7.4? (I also have an electronic pH meter, and it read 6.91)

Now the above readings were not allows like that, but that's where they are now (which is what I was after, before seeking to apply any other treatment

BTW since last writing another cat died (fungal)

It appears that the first 2 also suffered from "hole in the head" (my guess based on research thus far)

Yes 25 or so cats in 55 gal may seem like a lot, but they are mostly 2-3" fingerlings. My thought was to move them to a larger, dedicated (no aquaP tank (for now) when they get larger)

Perhaps a little more background... prior to today, there was a period of about a month where there we no plants in the 2 associated grow beds. That may have accounted for what appeared to be a spike in No2/3 and Am a week ago

Also, several weeks ago I added some duckweed to the fish tank barrel 'cos I heard fish like that as food. Not sure about cats. Well it turns out there were some small snails with the duckweed, and they have increased in number. Not sure if snails are harmful/toxic to cats or if they can coexist.

Also, I may have been a bit lax in introducing some rosy red minnows from a pet store, and not taking better care not to introduce the water from the pet store as well. Perhaps that is where the fungus/parasites came from?

I am open to quarantining the remaining cats, just not sure what medication to use. I'm a little worried about using salt after reading about another cat owner earlier in the thread - but hey, if that's what it takes, then I'll do it

So what meds/treatment help with fungus? "Hole in the head"?

Rest I will keep my tank pristine in the future... which may seem odd considering cats seem to prefer dwelling at the bottom in the sediment, etc. Oh well... live & learn... as long as I can stop the carnage I will be happy... don't want them to suffer due to my ignorance

Thanks everyone for your help!

Well, the treatment for fungus is basically to keep the water quality good, add salt to about 3 parts per thousand (like Colum said. If you have strawberries they will not like this but most plants are OK with it), and keep the fish as unstressed as possible... which is where you might have a problem.

You seem to have enough filtration for that number of fish, but even small fish need swimming room, and catfish are happier if they have plenty of hiding spots. Also, if they don't have plenty of space they won't grow properly even if you're feeding them plenty. Can you swap the bigger tank you were planning to eventually move them to into the aquaponics?

Snails won't hurt the cats but they will breed and cause plumbing issues - mostly obstructing pump inlet and clogging ball valves that are not full open. I got them in my system from some plants I added. I added some yoyo loaches to help control them in the tank, but they are still an issue in the growbeds, filter, etc.

NEVER add any fish to your system without a proper quarantine. They will bring all kinds of problems with them. I was paying top dollar for my channel cats from a reputable supplier, and the one time I took a shortcut I was rewarded with an ich infestation. At least 10 days in an isolated tank with 3-5ppt salt is what I do before allowing any new fish into my system.

Same with plants, they have water from the previous system. Rinse them well, put them in a tub or other isolation for 10 days or so and keep an eye out for snails, etc. Never add water from another (unknown) system to yours (like the water fish come in). Always net them into the Q-tank to minimize water transfer. Disinfect nets / other items before using in another tank. The water from my "reputable supplier" was full of malachite green and who knows what other pharma and chemicals to control fish diseases.

Thank you dstjohn99 & Mel!