I thought I had responded earlier to this, but either I did not, or my reply was eaten. Like Steve C, I had many fry grow up in the tank from the time they were spat out to full grown while I kept Frontosa. My only hesitation would be saying you'd be fine doing so with WC, mine were tank-raised and I don't know if this would be one of those things that is different between WC and tank raised. At 4" I can't see you having issues though