I bought a young flowerhorn about 3-4 days ago (approx. 2in from tip to base if tail) and he’s acclimated really well and swims around, follows my finger, has a ferocious appetite and all his black stripes have faded away from stress since i got him. I’ve been noticing he really likes to what looks like chew the gravel, is that a problem? slightly worried he might accidently swallow one because he usually spits it right out, should i change my substrate?