Goldfish aquaponics has much to commend it. The most popular ornamental fish on the planet, probably. Everybody loves goldfish and for many excellent reasons.
Of course, goldfish are not really a good choice of fish if you want to produce your own supper. More so, if you are looking to impress dinner party guests. They are nevertheless, perfect edible. It is not something I personally have ever been tempted to do. I, like most people, find trout, carp and tilapia far more appealing.
Top Ten Reasons why you should consider Goldfish Aquaponics.
Here are my Top Ten reasons why goldfish could be the perfect fish for your aquaponic system.
- Easy to breed. It is well within the capabilities of most fish keepers to successfully breed goldfish and raise good numbers of fry. This is of enormous benefit in keeping diseases at bay and adds a whole new dimension to the hobby. The threat of disease is, quite rightly, taken very seriously by the authorities. They possess the power to halt all fish movements that can, and usually do, have devastating effects on affected businesses.
- Readily available. Fish of all sizes are readily available throughout the year from a wide range of sources, both locally and globally. Production systems can be kept properly stocked at all times.
- Affordable. Compared to many koi most goldfish are not expensive to buy. This undoubtedly has helped make the humble goldfish one of the most popular pets in the UK.
- Easy to feed.A range of specialist flakes, sticks and pellets are available from several competing manufacturers. In addition, goldfish make very good use of many readily available, and easy to culture, live foods such as Daphnia, brine shrimp and earth worms.
- Water quality tolerant. Goldfish have a well-earned reputation of being resistant to poor water quality and less than ideal management. Although excellent water quality is always something to aspire to, if things are less than ideal, it is reassuring to know that temporary lapses in good water are far less likely to prove lethal to goldfish compared to many other species. Intensive fish production is always going to be a high-risk activity so try to avoid sensitive species.
- Wide range of varieties. Goldfish have a long history of selective breeding, most notably in China and the Far East. A variety of goldfish exists for many different tastes and is constantly evolving. Some have long flowing fins, some have no dorsals at all. There are a myriad of different colours and scale patterns.
- Excellent sales potential. Very popular in the ornamental trade. The UK and the USA have well established markets for goldfish. Both for ponds and indoor aquaria. As a consequence, sales are possible throughout the year. The importance of maintaining good cash flow throughout the year cannot be over emphasised.
- Indoor aquaria. There are two distinct markets for goldfish here in the UK. Fish for garden ponds and fish for indoor aquaria. This really helps to extend the seasons and makes goldfish sales possible throughout the year. On the other hand, one wholesaler of pond fish and plants that was a very good customer of mine used to do 40% of his annual turnover in May. This can have serious implications for anyone producing fish in a heated recirculating system. A steady state uniform production system needs a corresponding steady state market if fish holding is to be minimised. Large-scale live fish holding is both expensive and high risk.
- Warm water benefits. Although goldfish can withstand anything the UK weather system is likely to throw at them they do best under warm water conditions. The ideal temperature for growth is 21 – 23 °C. The aquaponic system has a clear advantage over pond culture in that temperature control is a perfectly feasible option. It goes without saying that greenhouse and poly tunnel aquaponic systems offer real advantages over outdoor ponds.
- Show quality fish. The existence of fish shows has lead to the demand for top quality fish that reach a set of agreed standards. These fish are highly sought after and can change hands for some serious money.
Types of Goldfish.
Goldfish are a member of the carp family, Cyprinidae, but are a separate species to common and mirror carp, Cyprinus cardio. Actually they more closely resemble the Crucian Carp, Carassius carassius. Controlled breeding over the centuries has resulted in many different goldfish varieties, but they all belong to the same species, Carassius auratus. They can usefully be divided into two main groups.
a) Single tailed Goldfish.
This group includes the common goldfish, comets and shubunkins. These are very active and hardy fish. They can survive in wild ponds and lakes but their bright colours do tend to attract the attention of predatory fish such as pike, perch and trout. Single tailed goldfish are an excellent choice of fish for outdoor aquaponic systems in the UK.
b) Twin tailed fancy goldfish.
The second group is a completely man-made group. They have been extensively bred over many years and a wide range of characteristics have been purposefully selected for. Bizarre fears include bubble eyes, pearl scales and lionheads. Naturally enough they are better suited to protected indoor aquaria rather than outdoor ponds. They will rarely survive the competitive natural environment.
Culture Conditions for Successful Goldfish Aquaponics.
Goldfish thrive in moderate to low water flow rates. In common with tilapia and catfish they can survive well in warm, static ponds. Although goldfish are capable of withstanding poor water quality we should all strive to maintain the high standards suggested by the Ornamental Fish Trade Association. These are set out below
- Temperature Range : 4 – 25 °C.
- Optimum Temperature : 21 – 24 °C.
- Dissolved oxygen : minimum 4mg/litre and preferably over 5mg/litre.
- pH 6 – 8.0. Optimum pH is probably 7.0 – 7.5
- Maximum unionised ammonia : 0.02 mg/l. This is not the same as total ammonia nitrogen (TAN) and shouldn’t be confused with each other. Find out here everything you need to know about fish ammonia.
- Maximum nitrite : 0.2 mg/l. This is a direct product of ammonia breakdown and, although less toxic, lethal concentrations can occur especially early in the filter maturation process.
- Maximum nitrate : 50mg/l. above background tap water levels. Some breeders of fancy goldfish advocate even lower levels.
If goldfish are to grow to their full potential, under warm water conditions, they demand ‘top notch’ water. In particular they consume an awful lot of oxygen under these conditions. Much higher even than trout. Warm water contains significantly less oxygen than cold so we are faced with a ‘double whammy’ effect. For this reason I would recommend the home operator does not exceed a stocking density of more than 20kg/m3.Breeding
This is not an article on how to breed goldfish. That will come later. I just wanted to stress that the breeding of goldfish plays a much more prevalent role in fish keeping than for koi. Goldfish become sexually mature in as little as 12 months and need little in the way of facilities. In many cases breeding is so prevalent that ponds can easily become overstocked. It is often the case that breeding needs to be controlled rather than encouraged. On the other hand, careful selective breeding has lead to the development of many new and exciting strains. If these varieties prove popular they need got be protected by advanced line breeding programmes. Equally new varieties, such as the butterfly tail goldfish, are constantly being bred and add continued interest to the hobby.
Goldfish, on common with carp, are omnivorous and generally require medium levels of protein in their diets. 30 – 40% protein levels are typical. They are a very adaptable species and can make good use of a wide variety of feeds. In a relatively small and confined fish system there is very little natural food production. It is wise to feed a complete pelleted food as a basic ration. Other ‘treats’, such as earthworms and Daphnia, can be hand fed on a more ad hoc basis. It is an excellent idea to supplement a diet of dry pellets with plants grown in a connected aquaponic system.
Goldfish do not have a stomach as such. As a direct consequence they benefit from a ‘little but often’ feeding regime. Automatic feeders therefore are essential if maximum growth rates are to be obtained. A slow steady, almost continuous feed, is much better utilised by the fish and helps to spread the load exerted on to the filtration system. As with all fish the smaller fish eat a higher ration per unit with than larger fish. They also have a greater demand for protein and a better feed conversion rate.
The global goldfish market is part of the huge and incredibly diverse ornamental fish market. Around 2,500 different species of fish make up the ornamental market with about 60% coming from freshwater. Over 90% of the freshwater fish have been cultured whereas over 90% of the marine fish have been captured. Goldfish represent an extremely sustainable crop with close tp 100% being produced on farms.
The market however, is dominated by about 30 different freshwater species that include guppies, angel fish, neon tetras as well as goldfish. The overall market value is huge and currently estimated to be worth $10 billion. It has been expanding for several years.
The main exporters of freshwater ornament fish to the European Union (2017) are shown in Table 1 below.
|Country||Value, 000’s euros||% Total EU imports|
Table 1: Main Exporters of freshwater ornamental fish to the European Union. (2017)
The main importers of ornamental fish within the European Union are shown in Table 2.
|Country||Value, 000’s euros||% of EU imports|
On a global scale the USA produces vast amounts of goldfish. Many are produced for anglers to be used as bait or for aquarists to feed predatory pet fish. These represent the lowest cost fish. At the other extreme. years of selective breeding and intensive culling has produced fish that are highly valued and displayed in specialist shows around the world. These can command ‘silly money’ and should not be used to calculate profitability potential. These values can fluctuate widely. Individuals are therefore recommended to carry out their own market research. It is true to say that there has been an increase in the higher end of the market as customers and producers become more aware of each other.
One important consideration when selecting a species of fish for any aquaponic system is the availability of young fry and fingerlings. Goldfish aquaponics score highly in this regard, more so than tilapia. When choosing a supplier it is preferable to pick one that carries out their own breeding as small fish cost considerably less and quickly growing in an aquaponic system. Fish of 2 -3 cm. would be ideal but most farms start selling at 5 – 7cm. Expect to pay 30 – 40p each for 5 – 7cm fish or 50 –60p each for 7 – 10cm fish. (2019 prices)
List of Goldfish Suppliers
- Hampshire Carp Hatcheries
- Fancy Goldfish Breeders – if fancy goldfish are what you’re after then find a local goldfish society and ask around. Local shows will often include auctions for surplus stock. If you cannot find a local club then do a search of groups on Facebook. It shouldn’t be too hard to find a supplier.