When planning a system there are several factors to consider, what is the optimal temperature range for the species you have chosen to grow, What size fish will you grow, is the species cannibalistic, will you sell Live Fish, whole Chilled fish, fillets, Distance to market, availability of good water and power supply, a power back-up system.
A system needs to be designed once you know the answers to the points in system planning.
Not all fish lend themselves to intensive culture, to ensure a successful experience in Aquaculture the species of choice must have the right balance. Quick Growth, Market Price, seed-stock availability, tolerate high stocking density, Robust, they also need to be approachable and not stressed by human interaction.
Running costs in Recirculating systems can be high, A system should be designed to use as little power as possible to achieve good water turnover rates, stocking density, one also has to ensure ease of harvest.
When we consider Return on Investment the cost of production is where many loss site of the end goal which is to be viable and profitable, an intensive fish production system is not an aquarium and needs to efficiently deal with high stocking density and high feed rates, keeping in mind you cannot sell high stocking density you can on sell kilos of fish produced, poor water quality is the main issue in any fish production having a system that allows easy control over the environment is the key. The 3 most important rules for food production is Control, Control, Control.