Okay, so I think that covers the "what are the basics"...
Now...the problem...one of my cories died today...I was doing a regular wc and noticed he was laying in the java moss, not moving but breathing heavily. He scooted off when he saw the gravel vac and I thought perhaps he had just been schooling with the endler's (they all school together). Before I finished siphoning the water, I noticed he was "floating" in the tank. He allowed me to scoop him up in my hand and as I carried him to a 2.5g heated/airstone qt I quickly set up for him, I noticed a red blister (not open ulcer but a blood blister like the kind a person would get) on his white belly and from underneath be also appeared to have a red internal stomach. He died half an hour later
I know I can not help him, but I am concerned about the rest to the tank population of cories and endler's. Could it have been random (all cories were added together a month ago), like he accidentally bumped into something and had internal bleeding? Could it be some type of parasite and now I need to dose the tank (I would like to avoid medicating if it is reasonable to do so, but if I must then I will for the health of the fish). I also noticed one other cory just laying on the sponge cover I have over the filter intake...but I didn't see any heavy breathing or signs of redness.
Anyone deal with this before? I didn't think to take a pic before I disposed of the fish...so sorry because I know that would have been helpful.
Thanks in advance for any guidance/help.





