okay many might now of my dempseys breeding only at 3in theyve had 5batches the thing is the othe tank mates would eat them so i finally got them there only tank but heres the problem i got river rock instead of sand like there old tank i also threw in there fry they search and gathered them already but i feel like there so small there falling in threw crack will this be bad for further batches?? will they loose there fry?? should i change substrate?? what are your exp??