[trashion]

So my friend had 2 ADFs in her 2.5 for less than a week. The tank was seeded with filter media from my tank for an instant cycle, but both frogs died. They didn't eat, and then they died. They both looked okay, albeit a little scrawny. Confusing, but okay. I've heard of this happening. I tested the water in the tank, and nitrites were a little high, but I assume that this was from the frog being, well, dead in the tank for a few hours before she came home. Ammonia was zero, and nitrates were around 25.

This is the gross part. She then LEFT the tank, stagnant, filter turned off, for a few weeks. GROSS! Ugh, there were snails, planaria, wiggly things, and GOD KNOWS what else in it. FINALLY, she broke down the tank, cleaned everything with hot water, and threw out the gravel (she wasn't a fan of the color anyway)

A few days later, we picked up a betta. I put new filter media from my established tank in her tank, and we acclimated the little guy. He seemed to be fine, but two days later, he's dead. My friend is really upset and feels like she should never touch another aquatic animal. Here's what I think might have done it in for the betta:

She bought it from Petco. (first strike) It was the Petco I used to work at, and I know very well those bettas are fed maybe 2 or 3 times a week. Upon getting it into the tank, she fed it EIGHT frozen bloodworms. Not good. The fish's only symptoms were that it just hung around on the bottom, and only moved when nudged with a net. It also refused to eat the day before it died. I'm guessing eating so many worms could have given it a serious digestive issue? Its scales didn't pop, but any redness or discoloration would not be obvious, as the betta had very dark, almost black coloration.

So what's going on here? What killed these guys? What should she do to ensure nothing dies again? She's really sad about this, and wants another betta, but isn't sure if she should try it.

Help!