This is my first time posting on the forum, and I am doing it out of an urge to gain some information from people obviously more experienced than myself.
To give a background on the problem, I had an establish 30 liter tank that had been going fine for around 10 - 11 months. I then had to go over-seas for business and the tank was left being cared for by my father for three to four weeks. I beleive he over-fed the little guys and upon my return I found I had a nitrite problem on my hands. I rectified this through emergency water changes and dosing the tank with prime. Unfortunately though I lost two fish (tigerbarbs) before the problem could be rectified.
It had been about a month since that incident and everything seemed to be going along quite well when I noticed that one of my bristlenose catfish seemed unwell and listless. He would sit in the corner of the tank and barely move for the entirity of the day, wouldnt touch food either. He had a red bloody mouth, red gills and a red anus. Two days later he was dead and was covered with very large white patches.
I have been told that due to stress, this poor guy contracted an external bacterial infection which essentially overcame his ailing immune system. It has been four days since this incident, and I have kept a close eye on my tank. Everything seems fine and all the fish seem quite hungry and happy but my friend (also a fish enthusiast) is encorouging me to dose the tank with an antibiotic and wipe out the bacteria present. This will obviously not only wipe out the nasty bacteria but will totally destroy my nitrogen cycle also. He advised dosing the water with prime during the treatment cycle, then upon completion give the tank a thorough water change, gravel clean, then add a nitrification supplement in a strong dose to start up the tank again. This all seems very risky and I dont want to do this if it is not needed. I dont want to lose any more fish via hitting them with truck-like quantities of antibiotics, then threating them by taking away their nitrogen cycle.
What advice would you guys have for this situation? Should you deal with the bacteria that caused a fish to die, or will it be okay as long as the fish dont get stressed out?