Hi guys, im new to the forum for posting, though i have been visiting and reading posts for quite a while, but now im in need of your expert advice and option. Basically its in regards to my corydoras fry (albino and emerald) if they have fish TB. Here is the histroy, i got 7 albino and 2 green cory from a friend around 17th April, they looked fine, no noticeable issues on them. I conditioned them with bloodworm tablets and other corydora foods either by SERA or JBL. I kept them in 3 groups, the 2 green together and 4 albino together and 3 ablbino togther. The green pair bred and layed eggs on the 9th may, the eggs hatched on the 11th and 12th may. I fee them liquid food for 1 week or so then moved them other fry food n micro flakes. There were around 200 plus fry i would think. I did 20% to 50% water change daily siphon up all left over food. But by week 2 going to week 3 i noticed some were dying, which i thought it was normal to loose fry as it has sometimes when i bred my goldfish. But i read up amd saw a few posts that people recommended that there is a layer of fine sand as i originally had bare bottom tanks. So i add about 1/4'' of fine sand as other members recommended. But that kept the morality rate going on, everyday at least 2 or 4 would be dead. I noticed some at times would be sluggish meaning u could easily catch them with your hands, but others were very active unable to catch with hand or nets at all. Those that were sluggish i noticed there tail was bent inwards. When i looked it up online people said bent tail is usually associated with TB. Like now my fry are 6 weeks old or 7 weeks old i dont expect them to be still dying. Their numbers has been reduced to around 30 to 38 of them. Today i just separated the bent ones and the straight n active ones in different tanks for me to see the behaivor or which else dies especially if from the non bent tank batch. what i dont understand is if i was fish TB, therefore i would at least see that the parents at least one would have bent tail or something showimg thats not normal right? The parents look healthy and eating n still breeding but now im not collecting the eggs until i can solve this with your help. my water temperate is usually around 25C to 28C. No need for heater as i live in the tropics as the climate is always 24C to 30C nothing less nothing more. so what you think can be the cause of those fry death at this stage plus bent tail but nothing apparent on the parents. the albino has also breed some are now 3 weeks old n some 3.5weeks , some are dying too but though i dont notice if the tail are bent cause they too small. my supply water is usually at pH 7 but my kH is usually 1 or 0, super soft water, i use sodium bicarbonate to raise the pH to keep it around 6.8 to 7.2 as after the pH falls. one of my friend says it's probably my water is too soft and lacking calcium and i should also try to giv them vitamins in their food to help boost them. what i want is to eliminate the chance of TB. Im not someone who keeps fish in poor condition, sometimes i would run a little behind water change but not since i had those cories. I always use a cycled sponge filter with them. Have gentle aeration too in their tank. I even tested the oxygen level, which the results says sufficent for most fishes. everymorning i would test my ammonia level before water change it would be around 0.5mg/L (ppm)or max 1ppm but i would still change 50% with fresh water. please help me out n let me know what you think is causing that. I will try to add photos later. The fry were in a 20G tank, water no more than 6inches high.