Hello guys, one of my previous bettas pasted away a few days ago, i think it was parasites or constipation his poo was stringy white. Anyways i got a new betta a crowntail , white and red , white tips it looks pretty cool :) , i just need a few tips i have a 3.5 gallon with a carbon filter , should i do a 25% water change a week ? or can i do every other week? no food is left at the bottom i make sure he eats it. and the food is aqueno betta pellets i feed him about 2-3 a day. and do i get rid of the bubble nests he makes ?