Fishy Facts

Frequent Fishy Facts for Friends

What fish are best for my aquaponics system? What do you recommend for my system?

   Answer- In one word? Tilapia.

Tilapia are the toughest fish species I have come across, in terms of water quality tolerance, stress, disease resistance, rapid growth, and ability to eat and thrive on almost any food. And perhaps most importantly, they are ridiculously easy to breed. They taste great. They are beautiful. They are social and non-aggressive. They are omnivores, and get more vegetarian the older they are. And as tropical freshwater fish that are not prohibited, they are one of the few edible fish practical for aquaponics that do not require CDFW consent. They have only one weakness; they have a lethal low temperature of 55 degrees F. 

Aside from that, catfish, carp, and sturgeon are also tough fish, and I have faith that native Sac perch will take over tilapia as the best aquaponics fish for California

 Do I need a permit or permission for buying or keeping fish in my system?

  Answer- If your fish are hobby tropical freshwater fish that are not prohibited, gold fish, or koi, then no. I advise to research CDFW yourself, and use discernment and common sense. 

How many fish should I buy?

  Answer- A good starting point is one pound of fish per 4 square ft of growing area, regardless of tank size. Tank size has very little to do with stocking density, since the plants are what remove nutrients from the systme, not the fish tank. Now, I have pushed the margin of this figure by at least four-fold, and season, type of fish, design of system, and method of solids control have huge parts to play in making an educated guess. I tend to stock my systems closer to 1 fish per square foot, knowing full well that the system will be taxed by the time they approach a pound. This allows some insurance in case some die, and the fastest growers can always be eaten to reduce the bio-load if things get soupy.

Are tilapia legal? What fish may I have in aquaponics system? (The most common question, hands down)

   Answer- Rules vary by state, and even how the rules are written is not consistent. This is a touchy subject, and very muddy to navigate a proper answer.

In California, any fish raised and sold for human consumption requires an Aquaculture Permit, and is subject to complete jurisdiction and any whim or opinion of the CDFW (Cal. Dept. of Fish and Wildlife), for approval or rejection. So if you wish to make a business of raising edible fish, contact them directly, and good luck with that. 

Now then, for hobby fish, the CDFW has a list of prohibited species rather than a list of allowed species. This means that if your desired fish is not on the prohibited species list, then it may be allowed for hobby or ornamental purposes, under the following basic categories, for freshwater species:

1. Koi and goldfish are exempt from all DFW regulations, save one: DO NOT RELEASE ANY AQUATIC SPECIES INTO ANY OPEN WATERS.

2. All temperate fish (other than koi or goldfish) require a stocking permit from DFW, and details and restrictions vary by county.

3. All tropical, freshwater fish that are not on the restricted list, are "legal" to keep. This 3rd category is designed for aquariums, and is the reason you can buy hundreds of different tropical species from a pet store. 

SPECIAL NOTE: 

The CDFW may make "policy" that conflicts with the "law", similar to a cop trying to enforce his "opinion" rather than the "rules" he is paid to uphold. Do not allow a public servant to bully you. Demand legal proof of "policy" if you suspect bullying, and then demand their resignation if they fail to supply proof. 

Now, in the case of tilapia, for instance, there are four species commonly farmed the table, namely o. nilitocus (Niles), o. aureus (Blues), o. mossambicus (Mossies), and o. hornorum (Zanzibars). Of these, Niles and Blues are specifically listed on the prohibited species list are thus positively illegal to possess in any and all of California [manual 671 title 14 line (9)(O)(1-4), page 10]. Mossies and Zanzibars are not listed as restricted, and ARE absolutely "legal" to possess, despite the "policy" of CDFW to fraudulently say otherwise. The wild population of tilapia in Southern California's Salton Sea are hybrids of these two species, and it is these two species that are farmed in Callifornia, with permission and approval from CDFW. In fact, it was the CDFW that is responsible for planting tilapia in open waters originally, as a natural method of controlling algae. Really?  Yes.

Often I have heard from both the public and CDFW that tilapia are legal in So Cal, and illegal in Nor Cal, with the specific separation of the Tehachapi Mts. There is no such division in any regulation that I have seen, even from a search of the official website, and CDFW personnel have also been unable to site the regulation, even though they hold fast that it is in there somewhere. 

On the other side of the "policy" coin, CDFW technically requires a stocking permit for any temperate species, although they are allowing leniency in this regard for aquaponics, for non-natives like catfish, bluegill, and hybrid carp, and for natives like sturgeon, trout, and Sac perch. 

What fish should I have in my aquaponics system?

   Answer- Great question, and I can only answer it with more questions. What do you expect out of your aquaponics system? Do you eat fish? What fish do you like to eat? Is your system outdoors, indoors, or in a greenhouse? Are you willing and desiring to regulate water temperature, using heaters and/or chillers? Do you want to breed future populations, or keep buying fingerlings? Do you want to make your own feed? Is commercial feed available in your area? What vegetable crops are you wishing to grow? Do you intend to get an aquaculture permit so that you can sell fish for the table?

The answers to those questions (and more) will probably allow you to make your own decisions. Personally, I live in California, and have a preference for Cal Native species, both for ease of climate tolerance, and for edibility and taste. I raise many species both native and non-native, but plan in the near future to reduce that list to only Sacramento perch, white sturgeon, and kokanee salmon.

How do I breed fish for my future fish supply?

   Answer- Tilapia will readily breed in an aquarium, with near 100% survival rate. Each female can lay 1000 eggs per pound of mother, every 3 weeks, for as long as the water is in the 80's and reasonably clean, regardless of daylight time, season, or competition. The mothers are mouth brooders, carefully tumbling the eggs for a week, then the young for another week. The fry are able to eat algae and food immediately, and simply start growing at an alarming rate. Typically, the fingerlings are 1" long in 1 month, and are able to breed themselves in 3-4 months. For tilapia, breeding is not a problem, over-breeding is. 

Channel catfish are mass egg sac layers, and the fry are also able to scrounge and eat real food immediately. It takes a little more work, but it is possible for a moderately large system to support catfish breeding. They breed in the spring as the water warms, so spring conditions must be replicated, and the fry are usually hatched in a protected, aerated, clear water tank, and fed powdered high protein feed for a month before rejoining an aquaponics system. 

Sturgeon also lay relatively large eggs, and the fry can immediately take to feed, but the spawning requires careful water temperature control, and hormonal injection. This species is best left to the pros, and is the reason the fingerlings are so expensive.

Most other fish suitable for aquaponics are larval spawners, meaning they lay a whole bunch of tiny eggs, as in 10,000-100,000 at a time, hoping that a few will survive. This includes all of the sunfish, like bluegill, bass, crappie, greenies, and Sac perch. Of this group, Sac perch are the easiest to get to spawn, and actually the spawn is not the problem. The problem is that larval spawners are born so tiny and weak that they can only eat live zooplankton for the first 3 weeks of life, and they eat a lot. Most aquaponics systems are designed to keep the water clear and free of plankton, so if it is your wish to spawn some sunfish, you will want to start a greenwater/zooplankton tank about 2 weeks before the spawn. This can be done, but it is not realistic for the average Joe to succeed.