Are you kidding? Sharks/Rocktails to 99 is the most common method of achieving 99. Depending on the status of both products in the grand exchange at its current state- you can even profit from cooking either of them, as Mantis stated.
Also, /OT:
This is Rs2Pictures - you gonna post one?
It also depends where you're fishing/cooking. For example, tuna/salmon is faster at shilo than at barb if you're banking; and cooking is faster at cook guild or rogue's den than it is at ge.
Idk about the other fish, but lobsters gives around 125k xp hour (that was in the cooking guild with access to the bank). If you do it at rogues den it might be like 110-120k xp/hour? Not 100% sure.