Stocking a 20 gallon tank?

in 20 gallon tank you could keep 20 fishes with size of 1 inch. if your fish size is 2 inches then that is 2 gallon per fish, so 10 total fishes in your 20 gallon tank if they are 2 inches in size. in my experience you could overstock your tank if you want to but beaware this will cause ammonia to build up faster. if you end up with overstock tank then you must change least 50% water every week. anyway i dont think that increasing the temp would kill the ich or ick. there is this medicine you could use which will kill the ick and you wont see it again on your fishes. the medicine is knows a ick clear tank buddies. you can find this at walmart and only cost $2-$3. make sure you read the direction before adding it to your tank.