We've been having troubles with the neon tetras in the 65 gallon tank. They are sick. at first it looked like a body fungus as the dorsal fins would get a white fuzz on them then the fish got sick and started behaving erratically, having troubles staying upright, as if they had a swim bladder problem, they would swim off on their own away from the group and hover as if sleeping, but much more twitchy than when they sleep, and soon after the sick fish always died.
We've been separating the sick ones to try to minimize the spread, and treating both the main tank and the quarantine bucket with Tetra/Jungle Lifeguard (it is sold under the Tetra brand in some places and Jungle brand in others) but it is not helping. At the time I'm writing this we've lost 6 of 10 tetras. We bought them in groups of 5 from 2 different shops. As cliche as it might sound I think now that our Neon Tetras are dying of Neon Tetra disease (a parasite) and that is why the medication is not working.…
I like to do a water change and a little bit of a vacuum of the tank bottom about once every 3 weeks. I take about 20-30% of the water out in the process and replace it with water usually at about the same water parameters. Often for me so far that has been dechlorinated tap water with maybe some distilled mixed in to bring the PH and/or TDS (total dissolved solids) down to match what the shrimp are used to.
In the near future I think I will start experimenting with re-mineralizing distilled or RO filtered (reverse osmosis) water. It seems that those who do it this way have better luck getting the CRS and other more delicate shrimp to breed.