A year-old NPT is going to have all sorts of detritus (mine does.) It settles on the bottom of your tank where it may serve as a source of nutrients for plants and microorganisms - and also release excessive CO2 (I've learned this the hard way) or you can remove it by vacuuming. Right now, it looks like it is just being kept in suspension by the constant flow from the powerhead. Some species of tropical fish (like a. borelli) get a kick out of poking around muck. To cories a mucky, mulmy substrate may pose a significant danger. To me, your tank looks perfectly normal. You just have to decide what's best for your livestock.
Fish doing Backflips
Hey, everyone I've been trying the Walstad method for a year now almost, but I feel as though right when things are going better something goes wrong. The plants are doing well finally and growing with new growth. Ammonia is 0 mostly due to plant growth, pH 7.4, temp 74, 10-gallon. I've had Corydora habrosus the whole time I've been doing this type of tank. I got 6 at the very beginning and over time only two have stuck around to today. I even got another 4 at some point 3 months ago to try and bring the school back up. All 4 new ones have died but these two fish have been resilient and stuck around. I also have cherry shrimp, ramshorn, and MTS that are all doing fine and breeding like crazy.
Now I'm worried because one of Cories are literally doing backflips. I'm thinking that it's due to constipation, as it seems most of my fish that have died seem to have died from a fish bladder issue. Seems like half my fish die within a few weeks when I get them and then if not then a few months later due to a swim bladder issue. I don't know what I'm doing wrong, I keep thinking it's because the fish are sifting the sand and eating stuff they shouldn't or maybe its the food. I don't know what to do any help would be amazing I just don't want to lose any more fish.
Video of cory doing backflips
Now I'm worried because one of Cories are literally doing backflips. I'm thinking that it's due to constipation, as it seems most of my fish that have died seem to have died from a fish bladder issue. Seems like half my fish die within a few weeks when I get them and then if not then a few months later due to a swim bladder issue. I don't know what I'm doing wrong, I keep thinking it's because the fish are sifting the sand and eating stuff they shouldn't or maybe its the food. I don't know what to do any help would be amazing I just don't want to lose any more fish.
Video of cory doing backflips
