Hi all. I need some help. I have a tank of corydoras, 3 of which were recent (ish) additions. 2 of my bronze’s started showing signs of fungal infection (white, fuzzy patches). I immediately treated the entire tank with antibiotics for a course of 3 weeks, along with a diet of boiled peas (no skin) and minced garlic bits. The patches completely resolved, and all of the fish significantly improved in terms of eating/diet, activity, and shoaling.
I came to feed them today and noticed one of my pandas completely on her side, having episodes of erratic swimming but staying on her side/upside down. I immediately scooped her out of the tank and into a little hospital tub with a dose of Seachem and an airstone. She is unable to hold herself upright, and flips out when I try to right her myself. The 2 bronze’s in the main tank are showing signs of stress, and their gills are varying degrees of red. I immediately did a 50% water change and tested my parameters using the master liquid parameter kit.
Nitrite - 0.0
Ammonia - 0.0
Nitrate - 40-80ppm
The nitrates have been on the higher end as I was told not to perform any water changes while the antibiotic course was going. They only got off the antibiotics this past week (maybe 3-4 days ago), and since I have continued with the fasting diet and salt dip once a week. I have no idea what’s going on or why their condition changed so drastically. I’m honestly at a loss of what to do, and I’m incredibly frustrated with the back to back issues I’ve been running into since adding my new fishies. This tank has been running for about 7 years now, and has corydoras that are 4+ years old, plus some plants (Java ferns, Anubis) that are as old as the tank itself. Besides these 3 Cories, the rest appear fine and aren’t displaying any redness on their gills or bodies. Even the 2 bronze that have reddened gills are maintaining activity, shoaling, eating, etc. They are not displaying any abnormal behavior. Any advice would be IMMENSELY appreciated.