OK I am new to this forum and as I search I am constantly prompted to post so...
I have had an interest in this subject for quite some time and I will share my experiences and observations. Not claiming to be any kind of expert but this is what I experienced.
I have owned ST in the past - never observed an unstable fish - period.
I have purchased ~ 20 IT anywhere from the size of a dime to ~10", raised them in groups up to 3 years at a time. The only consistent observation I can share is that their behavior with regard to coloration is a bit like Discus. The most subordinate fish has the most distinct, highest contrast coloration (vertical bars) - groups of 3, 5 or 11 it has always been the same for me. Get rid of the smallest/weakest fish and the next one in line takes its place in regard to coloration.
I have varied food (live, pellets, cut shrimp, shell on or off) , size of aquarium (80 -210 gallon), substrate, background, type and density of hiding places/cover and the observation above is the only thing i see consistently. I have purchased stable fish and added them to my group and they are unstable within a few days unless they are the smallest fish in the tank.
I added NTT (3) and they also became unstable with regard to coloration but over a longer period of time.
If anyone has ideas for me I would love to get advice on this. I have a giant tank with a lot of big black dats............except for whoever is at the bottom of the pecking order. whoever that is at the time looks awesome.
My water quality is excellent I have a large sump type filtration system no nitrate, ammonia etc.
I keep the dats with a large mellow arowana and flagtail prochilodus
I am always looking for information on this topic and more varieties and different individuals to add to the collection to try to get this tank looking like it should, any help is appreciated.