If you notice white salt precipitates in your system, these are signs of calcium buildup. Although calcium is not dangerous for your plants and fishes, it is an indicator for nutrient imbalance in your system.
Fish Species Have Different Behavior, Tolerance Levels, and Target Weight Per Fish Which Will Determine Their Fish Stacking Capacity
Fish species differ in how they adapt to stocking density and the space needed for them to grow comfortably. The first step in determining how many fish you can put in a 5 gallon tank is to have a per fish.
Some species like catfish have minimal requirements for dissolved oxygen although are very territorial. Tilapia on the other hand requires minimal dissolved oxygen as well but are less likely to attack fellow fish...
A High Fish Stocking Density Maximizes The Amount Of Fish Biomass In A Small Tank But Also Puts Stress On The Fishes
After Deciding, It Is Important To Adjust Water Flow, Aeration, and Filtration Capacity
There are different adjustments you will have to make to your system to adjust to a high fish stocking density or a low fish stocking density. These will allow you to maximize the productivity of your system and avoid getting fish kills as well.
Your water flow will need to be higher if you choose to go with a high fish stocking density. Alternatively, your water flow in the system can also be lower with a low fish stocking density.
First Adjustment You Will Need To Make Will Be To Your Water Flow
According to Dr. Lennard, for low fish stocking densities below 0.125 lbs/gal, your system will work with a water turnover rate of half the volume of your fish tank water per hour.
Before deciding how many fishes to put into a 5 gallon tank, decide on your goal for your aquaponics system. You can maximize your 5 gallon tank for growing fish by having a high fish stocking density.