Originally Posted by
Don in Virginia
You can check the TDS with a TDS meter, that's the only way I know. I have luck with the TDS at about 30 ppm. I understand that you're using RO and adding trace, but I don't know what that does to the TDS. Certainly the RO should take the TDS down to zero if it's working properly, but I don't know what adding trace will do. I always use R/O Right to bring the TDS up to around 30 from zero.
And yes, your fish could definitely be immature. Just hand on for a few months and see what happens.