Originally Posted by
smsimcik
Ok, I'll take a stab at trying to explain this. First off, I've grown out literally hundreds of juvie discus over the years. Some I bought, some I bred myself. So I have experience.
In your set up, if you do 50% or greater water changes/day, none of the fish will be stunted. You will have some that don't grow as big, but that's because they are genetic runts, not stunts.
If you do 50% water changes 3-4x/wk, all of the fish will be stunted to some degree. I guess it depends on your definition of stunted. But none of them will reach their full genetic potential.
Instead of a tank of 6-7" discus at one year, you'll probably have a tank of 5-5.5" discus at one year. If you are ok with that, then go for it.
I know you said you aren't talking about illness, but you should be. If you do every other day water changes like you say, you will probably be dealing with some disease problems whether you like it or not. Some of the fish will start flashing from gill flukes. Some will develop fin rot. Some will get cloudy eyes. Some will develop white bacterial spots on their fins and tail. They will keep eating and acting ok, but having even minor disease issues will inhibit their growth to some degree. Frequent, large water changes dilute pathogens and decrease disease issues dramatically. It's more of a issue with juvies than it is with adults.