What is going on??

[KTpoopenstein]

Basic tank history/info:

15g column, planted, whisper power filter 40 with filter foam and seachem matrix. Tank has been up and running for about 10 months, cycled and stable for ~6 months. Nothing has changed in 3 or 4 months. Had been stocked with 3 peppered cories, 6 serpae tetra and 1 platy (male) and 6 nerite snails. Back in Sept. (I think) I got 3 assassin snails because I had an infestation of ramshorn and bladder snails. The assassins killed one of my small nerites so I moved them temporarily to a 2g tank while the assassins did their thing. Once the pest snails were gone, I swapped the assassins and nerites and things were fine for a while.

A couple months ago (I don't remember exactly when) the platy died with no warning. Just dead at the bottom of the tank one morning. I checked the water parameters and everything was fine, but I did a PWC for good measure. A couple weeks later, one of the tetras was dead. Same thing. No warning, just dead at the bottom of the tank. The tetras have been kicking the bucket every few weeks since then. I'm down to one tetra, the three cories, and the snails. The latest tetra died sometime today or yesterday, but I haven't actually found him yet :-/

I'm not really sure what to do at this point. Is there any way to treat the whole tank for a variety of things without completely destroying my BB and having to go through the hell of cycling again? I don't even really like the tetras (they're boring and not particularly pretty), but my cories are full of personality and I don't want to lose them. Thoughts?

 

[anibis]

Since the fish aren't showing any signs of illness before they die I wouldn't treat your tank with anything. You need to know what you're dealing with (if anything) before you treat.

I would think if there was some sort of infection spreading through your tank all the fish would get it at once, it wouldn't be a death every few weeks kinda thing. It could be down to poor breeding practices producing a weak fish.

Just keep a close eye on your remaining fish. If they don't show any signs of illness (clamped fins, lethargic, not eating, fungus, ick, bloating, etc...) over the next few weeks then I think you are fine and just had fish that came from a poor gene pool.

 

[KTpoopenstein]

Since the fish aren't showing any signs of illness before they die I wouldn't treat your tank with anything. You need to know what you're dealing with (if anything) before you treat.

I would think if there was some sort of infection spreading through your tank all the fish would get it at once, it wouldn't be a death every few weeks kinda thing. It could be down to poor breeding practices producing a weak fish.

Just keep a close eye on your remaining fish. If they don't show any signs of illness (clamped fins, lethargic, not eating, fungus, ick, bloating, etc...) over the next few weeks then I think you are fine and just had fish that came from a poor gene pool.

It just seems abnormal to me for 6 fish to up and die for no reason within the course of a couple of months when everyone had been happy and I think healthy up until then. I honestly never saw much of the tetras. They always hung out under the driftwood in my tank and would dart away anytime I tried to look at them from the few angles you could actually see them. Honestly, to me they're no great loss since I never really enjoyed them, but I had grown a little attached to my platy. He'd been a trooper through an unexpected fish-in cycle and was my hardy survivor.

I did a ~50% water change yesterday and found what was left of the missing tetra stuck to the airstone inside the castle I have it weighted down with. It was mostly a glob of fuzz, so we have a fresh airstone and a freshly pruned and aquascaped tank now. Hopefully nothing else bites the dust...