Tilapia do have extremely sharp spines, but they are not nearly as long as a catfish. 8-10 mil would probably never get punctured by a tilapia. I have on occasion had doubled 4mil shipping bags get punctured from rough handling or a fish jumpiing into 2 inch deep water, but never triple bags. For large8"+ fish, I use doubled 5mil bags and never had a puncture, but those are always air-freighted and rarely get rough handling.
