Okay -- long story short, my little cardinal tetras are dying out on me.
Within the past 3 days, 3/10 tetras have died. I got 10 of them on Tuesday, then did a 25-30% PWC
on Sunday. It's now Monday, and 3 have died (1 on Saturday, 2 today: Monday). I finished cycling my tank almost two weeks ago, and today I checked my parameters to make sure they were all in line -- which they were. I have no idea what's going on! The only two possible things I can think of are:
1. The black molly (the only other fish currently in the tank) is definitely feisty and knows when/where feeding time is. However, I've been trying to feed the tetras 2-4 times a day -- using crushed up flakes (even smaller particles than what they come in) and mycine shrimp (also ground up). They never come up to the surface to eat (where the molly does), and I end up having to push most of their food into the water to be circulated around.
2. My LFS
gets their water from a different source than I do, even though we're in the same city. I would have thought that if this were a problem, it would present itself within the first 1-3 days, not a week later. Am I wrong in thinking this?
Today I actually got to 'witness' one of the tetras passing. I noticed him when I came home around 7:00p -- he was segregated from the rest of the school, near the top of the tank (they normally hang on the other side, near the bottom). I also noticed he was constantly gasping for air, which got me worried. That's when I checked the parameters, and all were fine -- even the dissolved oxygen, which was 8-12 ppm
. I left about 1.5 hours later, and returned again abut 4-4.5 hours after I noticed his odd behavior, only I came back to find the poor little guy on the floor of my tank.
What is going on?! This is my first tank and I don't know if there's something I'm doing wrong or something I should be doing differently