Typically an aquaponics system houses the fish in a confined plastic container underneath the gravel grow bed in which the plants are grown. In my opinion this does not harmonise with permaculture design methodology of trying to meet the need so f the creatures we husband within naturalistic environments in which they can carry out normal behaviors and lead rich lives.
Instead I propose the fish should be kept within naturalistic pond-like environments and appropriate fish species kept that will thrive within those conditions.
In New Zealand this limits the fish species selection to aquarium-style fish, with the hardy and charismatic goldfish the string favourite. These fish do well within large ponds outdoors as long as they are deep enough for the health of the fish, be well-shaded with vegetation and have a constant flow of water to avoid stagnation and low oxygen conditions. In New Zealand ponds deeper than 40cm need to be fenced (in urban sections).
In selection of a fish species you want to pick one that will thrive within this confined aquaponics habitat, can breed and carry out a natural life cycle and can obtain a lot of its nutritional needs from its environment. In this section I will focus on the requirements goldfish have within such a system and the possible uses of such a species. This knowledge transfers well to other areas - as goldfish are a common outdoor pond fish. Also considered are the red-finned perch introduced from England - which is an excellent eating fish - but requires a larger pond (so more appropriate to a more extensive aquaculture system. And the Giant Kokopu (as experiments have shown commercial rearing of whitebait is possible using them (but this is a specialist fish - so included more out of interest sake).
Instead I propose the fish should be kept within naturalistic pond-like environments and appropriate fish species kept that will thrive within those conditions.
In New Zealand this limits the fish species selection to aquarium-style fish, with the hardy and charismatic goldfish the string favourite. These fish do well within large ponds outdoors as long as they are deep enough for the health of the fish, be well-shaded with vegetation and have a constant flow of water to avoid stagnation and low oxygen conditions. In New Zealand ponds deeper than 40cm need to be fenced (in urban sections).
In selection of a fish species you want to pick one that will thrive within this confined aquaponics habitat, can breed and carry out a natural life cycle and can obtain a lot of its nutritional needs from its environment. In this section I will focus on the requirements goldfish have within such a system and the possible uses of such a species. This knowledge transfers well to other areas - as goldfish are a common outdoor pond fish. Also considered are the red-finned perch introduced from England - which is an excellent eating fish - but requires a larger pond (so more appropriate to a more extensive aquaculture system. And the Giant Kokopu (as experiments have shown commercial rearing of whitebait is possible using them (but this is a specialist fish - so included more out of interest sake).
|
|
|
Fish Food
By creating a natural pond environment that is well planted by overhanging plant will encourage a wide range of natural insect foods that can supplement the diet of your fish. This can be further enhanced by some of the following techniques:
- Blending up finely dicing cooked vegetables, rice and egg and freezing that as cakes to cut up for goldfish.
- Duckweed can be grown separately and added as feed (or collcted from a wild source).
- Worms (from a worm farm) can be fed.
- Self feeding soldier fly composters can be set up next to the pond (see video below).
- Or the benefit with goldfish is there are a wide range of commercial foods you can buy.
Goldfish
Goldfish are the best choice for an aquaponics pond in New Zealand. Native fish are small, slow growing and have life cycle linked to ocean migration. Introduced coarse fish (Koi and catfish) that would survive well are illegal. Other Coarse fish Perch, Rudd and Tench require a larger pond. Trout also require a lager pond (with cool flowing water).
Goldfish however are a common species - that is already widely distributed throughout most New Zealand waterways and is not considered as having a detrimental impact freshwater ecosystem (if they get out). While Koi make a beautiful pond fish alternative to goldfish - they are illegal and can not be kept in captivity (due to fears of spreading their range in the wild).
Goldfish grow to around 40 cm in length and are long lived (10-20 years in a healthy outdoor pond) and can live for 40 years if well cared for. They are bottom feeders and stir up the bottom sediments in their search for food. So it is good to have a sand or fine gravel substrate that will not cloud up the water - but still allow them to carry out their natural feeding behavior.
Within a planted pond connected to a aqauponics system - the filtration of the water and removal of excess nutrients should be sufficiently achieved by the plants of broken down by bacteria in the growbeds of the plants in the glasshouse. But the water returning to the pond is often via a slow passive channel - so it would be a good idea to set up a separate pump to a water feature that further circulates the water and oxygenates - and this can be connected to a filter to remove excess nutrients. A favourite design concept of mine is a naturalistic biodynamic flow form integrated into the water feature which combined with the water purifying properties of pumping water through the plant growbeds provides an optimal water-treatment design.
Goldfish can be bred using nets placed in the pond, which they will be attracted to spawn on in early spring. These can then be removed to a separate tank to rear the young goldfish.
Goldfish however are a common species - that is already widely distributed throughout most New Zealand waterways and is not considered as having a detrimental impact freshwater ecosystem (if they get out). While Koi make a beautiful pond fish alternative to goldfish - they are illegal and can not be kept in captivity (due to fears of spreading their range in the wild).
Goldfish grow to around 40 cm in length and are long lived (10-20 years in a healthy outdoor pond) and can live for 40 years if well cared for. They are bottom feeders and stir up the bottom sediments in their search for food. So it is good to have a sand or fine gravel substrate that will not cloud up the water - but still allow them to carry out their natural feeding behavior.
Within a planted pond connected to a aqauponics system - the filtration of the water and removal of excess nutrients should be sufficiently achieved by the plants of broken down by bacteria in the growbeds of the plants in the glasshouse. But the water returning to the pond is often via a slow passive channel - so it would be a good idea to set up a separate pump to a water feature that further circulates the water and oxygenates - and this can be connected to a filter to remove excess nutrients. A favourite design concept of mine is a naturalistic biodynamic flow form integrated into the water feature which combined with the water purifying properties of pumping water through the plant growbeds provides an optimal water-treatment design.
Goldfish can be bred using nets placed in the pond, which they will be attracted to spawn on in early spring. These can then be removed to a separate tank to rear the young goldfish.
Perch
Redfin perch are carnivorous and feed on a wide variety of foods ranging from small invertebrates (such as crustaceans, worms, molluscs and insect larvae) to fish. They are known to hunt fish either solitarily (by ambushing or stalking their prey) or in organised groups. Spawning occurs at night in late winter and spring (mid August to late October) when water temperatures reach 12°C, in quiet areas away from fast currents. They lay several hundred thousand eggs in a gelatinous ribbon amongst aquatic vegetation, submerged logs or other sheltered areas. The egg mass is unpalatable to most other fish and is hence generally protected from predation. Hatching occurs 7-8 days later, with juvenile fish schooling for some time to help avoid predation, before becoming solitary. Redfin usually take 2-6 years to reach sexual maturity, but some have been found to be reproductively mature at 1 year of age.
They are a great eating fish - but in a large backyard pond only a few individuals will survive (the rest will be eaten). They are also hard to feed as they need a constant source of live prey - although with a combination pf natural foods, worms, blackfly larvae and perhaps a supply of feeder fish this is possible. But considering how easily they can be caught wild in New Zealand - this may not warrant the challenge they present.
They are a great eating fish - but in a large backyard pond only a few individuals will survive (the rest will be eaten). They are also hard to feed as they need a constant source of live prey - although with a combination pf natural foods, worms, blackfly larvae and perhaps a supply of feeder fish this is possible. But considering how easily they can be caught wild in New Zealand - this may not warrant the challenge they present.
Giant Kokopu
Giant Kokopu are a native species in New Zealand that are the largest of the species that compose whitebait. Some populations of giant kokopu have formed land-locked - which has attracted the attention of them being used commercially to produce whitebait. This is especially because they are long-lived multiple spawners and due to their large adult size (40cm) can lay many eggs.
To keep them in a conventional aquaponics system is possible (if you get permission to keep them from DoC) but without knowledge and specialist set-up to spawn and raise juveniles you will not get any whitebait from an aquaponics pond survive. They like dense cover and are largely nocturnal. Feeding mostly on nocturnal insects and small fish. However they can get to know you and will also come out to feed in the day to offering of worms or insects.
To keep them in a conventional aquaponics system is possible (if you get permission to keep them from DoC) but without knowledge and specialist set-up to spawn and raise juveniles you will not get any whitebait from an aquaponics pond survive. They like dense cover and are largely nocturnal. Feeding mostly on nocturnal insects and small fish. However they can get to know you and will also come out to feed in the day to offering of worms or insects.
Wylie, M. J. (2011). Reproductive Biology of the Giant Kokopu Galaxias argenteus (Thesis, Master of Science). University of Otago. Retrieved from http://hdl.handle.net/10523/2015
| |||
| rearing_freshwater_crayfish.pdf |
Freshwater Crayfish
Koura in natural populations are omnivorous scavengers, consuming a variety of foods, with animal protein contributing the most to growth. Invertebrates including aquatic snails, chironomids, and mayflies are the main food source. Juvenile koura require higher amounts of protein in their diet than adults due to greater growth rate demands with invertebrates forming the bulk of their diet.
Koura occupy freshwater lakes, streams, rivers, and swamps, in mud or gravel substrates. Koura are nocturnal, moving into shallower water at night and deeper water column during the day. During daytime, they find shelter under rocks, debris such as cans and bottles, and vegetation. In soft sediments they may also excavate burrows or fan shaped depressions.
Koura occupy freshwater lakes, streams, rivers, and swamps, in mud or gravel substrates. Koura are nocturnal, moving into shallower water at night and deeper water column during the day. During daytime, they find shelter under rocks, debris such as cans and bottles, and vegetation. In soft sediments they may also excavate burrows or fan shaped depressions.