Selecting Fish For Your Aquaponic Garden

When selecting fish for your aquaponic garden there are a great many things you will need to consider and they will all have an effect on your overall system.

Water temperature is vital to many fish species and failure to comply with those needs will result in tragedy.  Goldfish and koi will live in much colder water than say … tilapia.  That doesn't mean that you can only raise decorative fish if you’re not in a financial position to heat a large fish tank but they do become a serious option.  Look into the species that live in the local bodies of water for ideas.  For example, trout and kokanee salmon can deal with some cooler waters and live in the lakes nearby my garden.  Perhaps someday I can use my aquaponic garden to help repopulate the dwindling sport fish numbers …

Cost of heating is however, something to think about.  The monthly costs to heat a large body of water and maintain it can be staggering.  If you don’t believe me, ask someone with a backyard hot tub what’s cheaper, buying it or running it.  My money is on running it, I've asked a few hot tub owners myself.  Sure you aren't going to need to keep your water quite that hot, but you will be heating more water and moving it around where it has many chances to shed heat that you paid for.



Edible fish will have different dietary needs than ornamental fish, so a different food source will be required depending on which you choose for your garden.  Will you be growing duckweed to supplement the diet of your fish or will you be purchasing something factory made for feed?  If you’re growing your own fish food you will need to be certain that all the nutritional needs of your fish species are met, there are a host of good websites and YouTube channels to help you with this.  If you've decided it would be better to buy premade fish feed you will need to make sure that it is food safe, if you plan on eating those fish or not!  The food that gets left in the aquaponic system will break down and begin to feed, or poison, the plants depending on how much of it there is and what it’s made of.  Even if all the food is consumed, it still needs to be food safe because when it comes back as waste … it becomes food for your plants.

How large will your fish grow and how much space will each one require to get to that size?  Different species of fish need different things.  A general recommendation for tilapia is as many as 1 per gallon, which seems crowded to me, whereas people will recommend a minimum of 10 gallons per koi.  If you’re going to put all this effort into your aquaponic garden, why not do just a little more research first?  My goldfish have somewhere around 2.5 gallons of water in the system per fish just because that’s how it worked out but they were just fine with only 1 gallon each before …

If you plan on marketing your fish, is there a market for this variety?  What will these fish be worth to you after the cost of feed, pumps and the rest of your overhead?  When you are getting involved with aquaponics on a hobby level this doesn't really matter quite as much but if you plan on making a business with aquaponics, this may make or break it.  In some regions the fresh produce will more than cover the entire running costs, however in others the really big money item will be the fresh fish.  I can’t say what’s going to be better where you are, but I will remind you to look into it before you get started.  Ah, the joys of a hobby garden … my fish are just helpful pets but if I were to sell them I suspect I would get enough to replace them with at least twice as many!

Once you've begun to establish what you require for a fish species, you can begin to design your aquaponic garden to meet those assorted needs and grow nice, healthy fish.  In the example of my garden, goldfish were selected for a few simple reasons.  First off I did not require fish that I could consume, and getting edible fish would have meant a great pile of paperwork to try that locally.  Secondly, goldfish are sturdy.  Temperature changes that would kill many decorative aquarium fish are of little concern to these hardy little goldfish.  Thirdly, even at their largest, a goldfish will only reach about 12 inches in length.  That meant I would be able to have larger numbers of fish, in a hobby sized garden, without overburdening the bio-filters or stressing out the fish.  Fourth and finally, as I have mentioned in many of my YouTube videos, goldfish are CHEAP!  I mean really cheap.  I could get one good quality koi for the same price as about 40 feeder goldfish so …  In a starter system, it still seems like a solid financial choice to go with a more affordable option.

Just a few things that you will want to bear in mind when first selecting your aquaponic fish!
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