hey man, fruit flies if not too severe can kinda spawn even from store bought soil. When i had that same problem i put up sticky strips all around the grow room and it took care of them over a week, caught them all before they laid more eggs it seems, left the strips up just in case until the end of my grow. Other than that foggers are the only ones that really work, just get the ones for indoors, and check the two active chemicals for effects and effects on humans, usually foggers will sterilise live bugs and any eggs they've laid. since your stargawg is still small you can probably spray it with neem oil, make sure you get the underneaths though... up to you ! dassit 🚀