The Top 5 Fish to Grow in Large Scale Aquaponic Systems
You’ve got the aquaponic bug and have a fish vessel of 250 gallons or more. Welcome to the DIY club!
If you are the type of person who cares more about how your fish tank runs rather than how it looks, then you probably want to choose a fish to optimize your system’s productivity.
In pursuit of smooth running systems and high output we are going to look at five of the best fish varieties for large scale aquaponics. First, let’s talk about the most important factors that you should consider before making your final fishy decision.
Temperature.
You need to know the climate of the place where your tank will be, as well as the highest possible temperature in summer, the lowest possible temperature in winter and how quickly temperature changes from day to night.
Knowing this, and the temperature preferences of the fish that you are considering, you can choose the right fish for your climate and budget.
Stocking density.
When figuring out how many fish to keep in a tank I like to use the rule of thumb of 1 lbs of fish by mass for every 10 gallons of water volume. You can push this, but it is a target that will both provide plenty of fertilizer for the plants and give you some safety buffer in terms of water quality and fish happiness. Keep in mind that whatever fish you choose will grow, so consider their likely harvest weight when stocking your tank.
Disclaimer: Before purchasing ANY fish, always check the legality of the species online with fisheries department of your state.
1) Tilapia
Tilapia are America’s favorite aquaponic fish for good reason — they grow quickly, have a great temperament, and are hard to kill. As omnivores they will eat all sorts of feed. They prefer warmer temperatures and grow especially well between 70 and 80°F, but are known to be fairly adaptable. Ask your supplier for a variety that suits your climate.
A challenge with tilapia is that they will become so friendly with the person who feeds them that harvest time can get quite emotional. A good rule: If your plan is to eat it, don’t name it.
The sentiment that tilapia ‘taste like mud’ is unfair. They get this reputation because they are so tolerant of low quality feeds and the poorly filtered environments that they are often farmed in (where other fish would just die) that they can take on a poor taste. When they are fed a high quality feed and live their lives in a clean, ecologically stable, well managed aquaponic system tilapia taste great. This tolerance of variable water quality is one of the things that makes them such a great choice for beginner aquapons. Some varieties of tilapia, if bought as fingerlings from a reputable US farm, can grow to plate size in as little as six months. However, tilapia are illegal in some states, so check online with your state fishery department before ordering.
With a little know how it is possible to breed your own tilapia, but this can be counter-productive. When in breeding mode the males get aggressive and the females stop eating, which is not what we want for aquaponic plant production! But you may want more fish one day, so it is nice to have a low cost option of obtaining them.
If you can guarantee an average tank temperature of above 70°F and that it will never fall below 60°F (you may need a heater) then it is hard to top tilapia as an edible aquaponic worker fish.
2) Rainbow Trout
Rainbow trout are my favorite fish for one reason — they are delicious!
You should only consider this fish if you live in a cooler climate. In an IBC system in Melbourne, Australia I grew trout from fingerling to plate-size over fall, winter and spring (9 months). The tank was normally around 60°F, (perfect trout temperature), thanks to a combination of shade, insulation and the normal seasonal climate. Rainbow trout will handle a temperature range of 45–72°F, but keeping it close to that 60 mark will maximise aquaponic veggie production and fish comfort.
Rainbow trout evolved in mountain streams and are happiest in clear, well circulated water. So, unlike tilapia, trout will not handle dirty water well. They prefer well oxygenated water with a dissolved oxygen level that never falls below 5.5ppm. For this reason, it is a good idea to provide additional aeration to your trout tank.
You might think that all this makes trout a little too high touch — but if you are up for the challenge they will reward you with great taste and value.
Fingerlings will usually cost one or two dollars at a trout hatchery, while buying a full sized trout at the supermarket can set you back over $20. I guarantee that if you grow your own, using a high quality trout pellet as feed, the freshly harvested fish will taste better than anything you can buy. As my baby sister told me when she was fourteen and fussy “This is the best thing I’ve ever eaten!”
3. Channel Catfish
Catfish are a legendary part of the cuisine of many areas of the USA, notably Louisiana (where tilapia are illegal). You can keep them in an IBC sized tank of 275 gallons or more, but due to their their potential length you shouldn’t have a tank any smaller than this. If you are thinking about stocking tilapia, a few channel catfish can make a great companions. They are peaceful tank-mates and will eat any leftover feed that sinks to the bottom. This is very useful as it will minimize the level of decomposing solids in your tank — helping to protect the balance and productivity of the ecosystem.
They will grow optimally in a similar temperature range to tilapia (70–80°F), and will stop eating if the temperature falls below 55°. Breeding them is difficult, but not impossible.
Catfish don’t have scales like other fish, so handling should be kept to a minimum and you should be extra gentle. Their skin, whiskers and calm demeanor makes them intriguing to watch and fascinating for kids.
4. Goldfish
Obviously, goldfish are not edible (unless you like stew), but they are still worth considering! No matter what fish you choose, nine tenths of the food you get from your aquaponic system will be plant-based. Goldfish are the perfect low-maintenance candidate for optimizing those plant yields, and if you aren’t going to eat them, you can name them!
In a big tank, they are very easy to keep. Goldfish, a relative of carp, are great at tolerating temperature swings to both the high or low end of the temperature range.
However, as with all fish, you should still target the perfect temperature (70°F for goldfish) to optimize feeding, pooping and veggie growing. If you are a lazy Aquapon and let your pH drift down slowly over time, goldfish will be more forgiving than most — but don’t be lazy! Goldfish might be able to survive almost anything you throw at them, but they will reward optimal care by driving better plant yields.
They are also colorful, pretty to look at and really fun as pets. They are legal everywhere, cheap to buy, and tremendously easy to find. It is worth paying a little extra at the pet store to avoid the ‘feeder’ goldfish, as these can often bring disease into your tank.
5. Jade Perch
The Jade Perch is a native Australian fish that is becoming very popular in the aquaculture industry. It turns out that this fish is great for aquaponics too.
It is difficult to find in the U.S, but if you can get it you should give it a try. Some reasons for its popularity are taste, hardiness, growth rate and nutrition. When fed feeds that are high in omega 3, Jade Perch is better than any other fish at retaining it and providing you with a nutritional meal at harvest time.
Jade perch will grow fastest at temperatures between 75–80°F, and will stop eating below 65°F. Like trout, they will not breed in captivity and will appreciate some extra aeration. If these conditions are met you can expect to harvest them in under 12 months.
If popular Australian aquaponics pioneer Murray Hallam were a medieval knight, he would fly an image of this fish on his battle standard — he absolutely loves it. By extension, most Australian Aquapons love it too.
These are just five of the options you might consider. If there is a local fish species that lives in the streams near where you live, then it is probably a perfect choice for your climate. If you are willing to spend more money on more complicated aquaculture equipment or bigger tanks then you could even consider fish as fancy as barramundi or pacu. But, if you are starting out, the five fish mentioned are among the most popular for a reason, and are great partners in the continuing of your aquaponic journey.
Originally published at blog.grovelabs.io.
