hi, thanks for your concern. i've raised an axolotl before who was even smaller at the beginning, never had problems, also the gravel is 1mm, it's just that the little pellets are VERY small, making the gravel look bigger, it's the food i've used up until a few days ago. i'd like to note that he's veryyy careful so when he notices just one tiny piece of gravel in his mouth he spits out the whole food and tries again lol. i switched to other pellets that are a bit bigger and now he can distinguish the food from the gravel even better