Here's the story:

My dad built a large 20 by 20 deep water reservoir several years ago before his demise.

Now there's a working borehole which has reduced or limited the function of this water reservoir to a mere rest-point for pets, etc.

I'm seriously looking for aquatic business ideas that requires very minimal attention and with very low mortality rate.

I'm currently looking at rearing catfish, crayfish, or prawns but needs better ideas as the well looks too large for raising catfish no matter the kind of steps that's built in it.

miracle4:
Here's the story:

My dad built a large 20 by 20 deep water reservoir several years ago before his demise.

Now there's a working borehole which has reduced or limited the function of this water reservoir to a mere rest-point for pets, etc.

I'm seriously looking for aquatic business ideas that requires very minimal attention and with very low mortality rate.

I'm currently looking at rearing catfish, crayfish, or prawns but needs better ideas as the well looks too large for raising catfish no matter the kind of steps that's built in it.

Catfish remains your best bet and ensure to secure the reservoir lest the become food for snakes.
Buy some fingerlings, pour them there and forget about them totally. check back after a year! The strongest would have survived

can you share pictures for better viewpoint? Cage aquaculture is the best bet for rearing fishes

I have added the pictures to the original post. thanks

matrixme:
can you share pictures for better viewpoint? Cage aquaculture is the best bet for rearing fishes

I've added it to the main post.

it's covered. So you can't do anything aquaculture wise in there. Fishes need light too sometime. And for ease of management.

Tilapia fish..no need for feeding..drop and go