I know some rbta's and gbta's get dyed so they're very bright when they come in the store, but it fades with time, and sometimes the host doesn't do so well with being dyed. I don't know if you could do it with acros, softie and nems because they take in the water to fill their tissue up so unless if you're literally dying the skin on the outside I don't think it'll work and if you do that, you'll most likely kill the acro by covering up the zooanthelle. JMO, I don't know for sure.