So I found an old post on aquarium co op on how to treat fungus with ich x and erythromycin. On the 10th I dosed the 20 gallon tank with 10ml ich x(5ml per 10 gallons as per directions) and 2 packets of erythromycin following their directions. I had an ammonia spike yesterday, the 11th, of .25-.50 reading and did a 50% water change and am using fritz complete to bind up any ammonia that might re occur and I re dosed ich x and erythromycin. I'm thinking the ich x and erythromycin either crashed the already present bacteria colony enough for a spike or the deaths finally built up. Although I'm hesitant to think it crashed the cycle since there has been no nitrite present... Also on the 11th the cory I posted in the picture with the clamped dorsal fin(the fry still had a dorsal fin it was clamped down) passed away and so did a few of the younger fry which is what I think caused the spike of ammonia. I haven't had any deaths or any signs of fry in distress since yesterday. I'm going to re check parameters today and go from there. If there are no other signs of fungus or illness I'm going to re dose the fritz complete if the ammonia is present to bind the ammonia up and to let the bacteria colony increase to meet the bioload as long as there is no off behavior or signs of illness. The fritz complete acts like prime does and binds any ammonia. Are there any other suggestions you might have? I retested the parameters and it was showing .25-.50 ammonia 0 nitrite and 10-20 nitrate with a ph of 7.4. I just read on the fritz FAQ and it states that it doesnt release the ammonia back into the water column that the ammonia continues into the nitrification process which is kind of confusing. My thought when dosing the fritz complete and not changing the water right off the bat is just that of a fish in cycle. I figure as long as I can bind the ammonia to make the fry safe then its giving the bacteria time to catch up to the bioload. Am I off in this thinking in this application do you think, even if the ammonia is made inert? Mind you this is not preferable just the situation I'm stuck in that I wasn't expecting. I'm just hoping to do the right thing and make the best of it. I'm also hoping that by buying time I'm giving the medication time to work. On a positive note I haven't lost anymore fry and there have been no more signs of the fungus on any of the corys that are swimming around or the ones that have passed. @nabokovfan87 This tank is only corydora fry. It's their grow out tank. It has a shallow layer of black sand on the bottom and terra cotta feeding trays and a few pots for hiding in(all from the already seasoned 10 gal tank for the beneficial bacteria). It has 1 sponge filter rated for a 40 gallon tank and 2 small sized sponge filters, I'm not sure what they are rated at. The bigger sponge filter was cycled/seasoned for months and holding the 10 gallon it was in at 0 ammonia 0 nitrites and 10-20 nitrates. I tested that tank right before I combined the 10 and 2.5 gallon. I run the control on the sponge filters on a pretty high setting right after I put in the meds and or any dosing of water conditioner to increase aeration then lower it so the corys can go up and down the glass like they like to. One of the smaller sponge filters had been in my 55 gallon for occasions such as this when I needed the extra cycled filter and the other one wasn't cycled yet. I also have a large pothos vine with a good root system that came from the 10 gallon so I'm assuming it had bb on it in there and various java ferns to help with parameters and oxygenation. I'm feeding ground up ocean nutrition fish flakes for all tropical fish and great for herbivores and it has a high protein content too. I dont know how to quatify how much im feeding. enough for them to eat but not enough to be there to decompose. I also have ramshorn snails and a shrimp in there to help consume the left overs if there are any. The tank doesnt have mulm for the fry i just make sure I feed them atleast twice a day. I also watched a video from steenfotaquatics stating that salt is bad for corydora since they have scutes and process everything differently than regular fish and the salt can cause permanent liver or kidney damage or death...
The video below states that in treating the fungus the medication can be left in for 5 days then changed out in 25% increments or with carbon.Thank you, I really appreciate your advice!
https://www.aquariumcoop.com/blogs/aquarium/fish-fungus