Backyard Aquaponics
A place to discuss aquaponics

I am wondering if there is a general rule of thumb as to how much space fingerlings need, vs, 1 month old fish, 2 month old fish, etc. For example: 100 fingerlings need 150 gallon of water, at 1 month 1.5 x original size, at 2 months 2x original size, etc.

Are tilapia top feeders, middle feeders or bottom feeders when raised in a pond/tank? Judging by the shape of their bodies I would guess top and middle feeders. Is there another kind of fish that can be raised in the same tank with tilapia that are bottom feeders, grow about the same rate as tilapia, need about the same amount of time from fingerling to frying pan and will not eat the tilapia? I know that adding another kind of fish into the picture would reduce the number of tilapia that I could put in the tank but it might make the loading of the tank easier. It might also be nice to have a variety of fish to bread.

Is there an ideal depth for a tank? does it vary on the size of the tilapia?

Is it possible to centrifuge the nitrates out of the water, i.e. separate the fish waste from the water using a centrifuge?

base your fish load on your filtration, and the size you plan to grow the fish out to... younger fish consume a higher amount of food for their body weight and are more active..
i've seen my tilapia eat from the top, middle and bottom.. they have been cohabitating with yellow perch and bluegill,, no issues.. the tilapia grew a bit fast than most of the yp - i got the tilapia at 1" and the last batch of yp at 3".. the yp have kept the tilapia breeding under control
my tank is around 24-26" deep.. i probably wouldn't go much lower than that.. maybe 18" minimum..
i don't think a centrifuge would remove nitrates, your plants will do that, and bacteria will convert the ammonia that the fish produce into first nitrites then different bacteria convert that to nitrates.. read up on fishless cycling, if your confidence in your research is high, you can cycle with fish
a swirl filter or radial flow filter will remove some of the solids, and don't require the energy a centrifuge would need