Cold vs Warm Water Systems

Your first decision regarding fish will depend on your local climate and your willingness to cover and heat the system. Cold water aquaponics tend to produce slightly lower yields and will only work for hardy fish species, but heating is greatly reduced to only fall and winter growing periods in most areas. Warm water aquaponics requires supplemental heating in all but the warmest and most tropical areas. Fish species that require warm water include almost all ornamental types and the fastest-growing edible varieties, while a few high demand and higher cost species like rainbow trout require a cold water system instead.

Watch Out for Breeding

It’s a common assumption that the rapid sexual maturity and fast-paced breeding habits of fish like tilapia make them ideal for a self-sustaining aquaponics system. However, having your maturation tanks constantly fill up with new generations of fry and fingerlings is not necessarily a good idea. First, fish in each life stage require different feeding styles and amounts. Juvenile and adult fish easily out-compete the fry for food, not to mention often eating the eggs and fry as food as well.

Harvests are also much more complicated and time consuming, and therefore less profitable, when mixed ages of fish are all combined in a single tank. It’s possible to grow multiple ages of fish in a tank by stocking percentages of the total stocking rate in multiple additions of new fry. By adding a quarter or more of the total population all at once, there is a distinct size difference among generations. This allows for easy net removal of just the most mature stock. Free breeding leads to many mixed ages, resulting in underweight fish that are still just large enough to get caught in the harvest nets.