Tilapia.
I did not.
I was the engineering side of things. Things like how to grow the fish and how to make the ponds etc under my jurisdiction. But even after you grow the fish, got to sell it. That one is not easy.

The main problem is this:
If you just want to farm and sell to midleman, then you must be very efficient because your profit margins will be razor thin. For example right now harga borong is RM14/kg. Means the middleman probably will buy from you at rm13 max. And that means you as farmer must have RM12 cost. Else you grow the fish for 6-8 months but can't even get rm1/kg profit.

If you want to distribute as well, you better find some good sales people. Because restaurants don't like to have their stock interrupted. So they tend to stick to 1 vendor. If you just start out, you have to somehow compete with those fellas in the market for 20 years. A lot of goodwill to catch up on. Not to mention that middleman/distributors have to invest additional for storage of live fishes and buying lorry/hire staff to deliver.