Bloated/prego/parasites in Danios?

Tank size: 75 gallon
tank age: 6 months approx
pH: 7.6ish
ammonia: 0
nitrite: 0
nitrate: had been high, 40-80ppm but denitrate and down to 5-10ppm
kH: ?
gH: ?
tank temp: 75


Fish Symptoms (include full description including lesion, color, location, fish behavior): 3 of the 6 danios look swollen, as if pregnant or something. None have raised scales, all swim and seem to interact fine. All eat. Just a few of them and especially one look bloated with stretch marks.

Volume and Frequency of water changes: at least once a week 25% or more

Chemical Additives or Media in your tank: denitrate, carbon, weekly use of stress zyme. Two canister filters, one has inline UV sterilizer on the return flow.

Tank inhabitants: the danios are glofish so there are 2 glofish sharks, 6 glofish danios. Non-glofish are 5 yoyo loaches and 3 kuhli loaches. One little tiny type of catfish that is basically a sucker fish but only grows to like an inch, seen it on a recommended algae eater list but cant recall name.

Recent additions to your tank (living or decoration): none

Exposure to chemicals: none

Digital photo (include if possible):

This looks genetical to me as the fish age they become deformed, part of the problem with glow fish I suspect

Its possible..., I have seen specifically other glofish danio images on the net that look similar, maybe not as explosive as the pink one. Could it be constipation?

. I never really paid a whole lot of attention to the food, I do usually get whatever looks and costs on the more higher side, assuming I couldnt go wrong there arrogantly, possibly. Long story short, my 6 yr old daughter wanted a hamster but I thought she should start out small and learn the responsibilities of having a pet, so I thought some fish and they these glofish. I got a 5-10 gal tank and a few glofish, thinking valuable life lesson for her. Little did I know it was about to be a life lesson for me and I shouldve went with the hamster.

A week passed, her little tank was not clear, stank, I didnt realize your supposed to cycle first so that was the first sign of maybe bad idea. Fish all made it, I used some precycled water bought in jug from petsmart. By this time I am fully dealing with the fish. After another week I get the feeling the small 5-10 gal tank isnt ideal and the fish are miserable. Thanks to covid, I wasnt able to return any of this stuff because they stopped in store returns for some time. So now I have these unhappy fish in a small inhumane tank that the petstore wont return so I have to keep them alive to return them when they do....

Fast forward to now, the setup is now a 75 gallon tank with an fx4 filter and penn plax canister, in the basement where my home gym used to be, and the daughter got off scotch free, because fish for a first pet turned out to be a horrible idea. I assumed, drop food in once a day, learn responsibility, perfect. There are so many, like infinite other areas to tend to in a fishtank, I even gave a shot at live planting with dwarf grass.

. Anyways, so I am here now and am realizing maybe they needed diff types of food. Usually Id thaw out some bloodworms & brine couple times a week. In between Id do a mixture of loach wafers and staple food or pellets. I am considering running up to store and getting some peas, or to petco for some probiotic new spectrum or something that will make em poo just to get that possibility out of the way, because although I hardly sit and watch specifically for a poo, I cant recall the last time I seen them pooin.

. Yesterday the big pink one appeared to be pooin but it seemed like it was more white and thin string thing just hanging flappin in the wind(water) as she swam...which would make sense if she is eggbound with tons of eggs because how attractive could that be (jk).