Manual for SMALL FISHFARM.pdf

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Manual for SMALL FISHFARM

Manual for

SMALL FISHFARM

SMALL FISHFARM 2003

Introduction

The SMALL FISHFARM enables persons to raise fish for their own

consumption It requires access to a sea a river or a lake with clean water

Technical background

The SMALL FISHFARM can provide a good supply of fish protein for a limited

number of persons while avoiding adverse effects on the fish and the

surrounding waters

The SMALL FISHFARM is constructed for extensive (rather than intensive or

semi-intensive) cultivation techniques The fish are not fed artificially but live

from algae plankton weeds and detritus that occur naturally in the water and

on the sea floor

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This low-impact method results in somewhat slower growth However because

the fish are less densely populated there is less competition for food and spacewhich can cause faster growth rates for individual fish This is useful in selective

harvesting Intensive or semi-intensive techniques raise the fish uniformly faster

by adding feed artificially which also enables denser stocking but this will

negatively affect the well being of the fish Also adding feed only increases

growth rate to a nominal extent with a system such as this And if the farm is

overfed the ecological balance can be disturbed and low oxygen conditions will

result

Construction

The SMALL FISHFARM is modular allowing multiple units to be joined

together Three polyethylene pipes are fixed in a triangular arrangement end to

end using rubber corner fittings They provide the floats that hold the fish netsThree thinner pipes erected from the corners meet in the center to provide

support for the top net while also adding further rigidity to the construction All

the materials are non-corrosive and non-toxic

If one raises species that feed off the sea floor the net must be open in thebottom This is the case with this version of SMALL FISHFARM The net is

somewhat longer than the depth of the water and is weighed down using heavy

steel chains woven along the bottom In order to be able to lift it when collecting

all the fish at once or to check the net for damage ropes are attached in

different places to the end of the net These can be pulled up through the ring

that is suspended at the center of the construction The farm is held in place

using three anchors marked with buoys Mussels can be placed along thebottom where they will feed off the fish droppings thereby keeping the area

cleaner

Fish

A large variety of fish can be raised with the SMALL FISHFARM but some areespecially well suited In addition to ones taste and preferences the choice

must depend on the salinity temperature and quality of the water One must

also consider the other organisms that inhabit the water including algae

seaweed plants and other fish species So as to not disturb the trophic systemit is important to use a fish species native to the body of water being considered

Furthermore some species require maintenance and feeding while others - if





the setting is ideal - can be left more or less to themselves

For common carp raised in an extensive culture successful stocking density is

around two fish per square meter of surface area First stocking size should be

a minimum of about 15 cm in length Although growth rate varies with size it is

fast enough to harvest fish every year as long as they are reproducingsuccessfully Carp will usually reproduce with one major spawning season per

year during spring or summer The male-female ratio should be about 12

Other possible fish species are pike zander trout salmon (these species are

mainly carnivorous and will have to be fed) tilapia catfish (both of these are

very hardy and can live in low oxygen conditions) grouper (marine) milkfish

eel and many others

Corner fitting

The nets are hooked on to theknobs





The chain weighs down the net

Anchor and buoy

Ropes fixed to the bottom of the

net





Fish net fixed to the construction

Swan mussels

(Anodonta Cygnea)





Common carp

(Cyprinus Carpio)

Nets

The drawbacks to cultivating any finfish in nets include the fact that the small

mesh size required for reproduction will inhibit good water circulation it will

become covered in algae and subsequently respiring bacteria quite quickly and

the bottom will be covered in fish waste This will also cause the oxygen levels

in the enclosure to become low which can be unhealthy or even fatal for the

fish and other organisms However by making sure the area of the farm haslots of plants and by stocking a few fish that eat the algae on the net this

problem can be avoided Another possibility is to use a larger mesh size in the

main area for better circulation and either restocking each year or having asecondary breeding area with a smaller mesh size used only for spawning and

rearing the juveniles to a certain size

Extensions

The SMALL FISHFARM can be extended with a small spawning area

connected to the main net The spawning area must provide a shallowheterogeneous and protected environment for spawning and for the growth of

the larvae and juveniles In the case of carp this area must be no more than 30

cm deep and be densely vegetated The carp will spawn between the plants

The spawning area should have a fine mesh size to prevent the offspring from

escaping however no mesh size is small enough to retain all the eggs and

larvae but this is not a problem because of the abundance of eggs As an

alternative to this method one can move the reproductively mature fish at theappropriate times to an external enclosure where they can spawn





For more intensive breeding a feeding automat can be added This requires

access to electricity which can be difficult

One solution could be installing a solar panel or a windmill including a battery to

store the energy

More SMALL FISHFARM units can be coupled together at the vertices to formhexagonal or rhombic shapes

Maintenance

Many fish species will themselves keep the nets clean from algae and weeds by

feeding off them If they dont some cleansing will be necessary Occasionally

the nets should be lifted and checked for holes and other damage

Sick or wounded fish must be removed from the farm

The largest adults should be harvested first

Component list

3 polyethylene tubes Oslash 20 cm thickness 11 mm length 4 m3 polyethylene tubes Oslash 9 cm thickness 5 mm length 233 m

corner fittings in rubber

27 bakelite knobs

polyethylene foam

12 x 4 m black nylon net mesh size 2 x 2 cmnylon thread

12 m steel chain3 anchors galvanized steel

3 black buoys

11 mm nylon reinforced rope

bolts and nuts

15 pc common carp (Cyprinus Carpio)

100 pc swan mussels (Anodonta Cygnea)





SMALL FISHFARM Bremen Germany 2003

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This low-impact method results in somewhat slower growth However because

the fish are less densely populated there is less competition for food and spacewhich can cause faster growth rates for individual fish This is useful in selective

harvesting Intensive or semi-intensive techniques raise the fish uniformly faster

by adding feed artificially which also enables denser stocking but this will

negatively affect the well being of the fish Also adding feed only increases

growth rate to a nominal extent with a system such as this And if the farm is

overfed the ecological balance can be disturbed and low oxygen conditions will

result

Construction

The SMALL FISHFARM is modular allowing multiple units to be joined

together Three polyethylene pipes are fixed in a triangular arrangement end to

end using rubber corner fittings They provide the floats that hold the fish netsThree thinner pipes erected from the corners meet in the center to provide

support for the top net while also adding further rigidity to the construction All

the materials are non-corrosive and non-toxic

If one raises species that feed off the sea floor the net must be open in thebottom This is the case with this version of SMALL FISHFARM The net is

somewhat longer than the depth of the water and is weighed down using heavy

steel chains woven along the bottom In order to be able to lift it when collecting

all the fish at once or to check the net for damage ropes are attached in

different places to the end of the net These can be pulled up through the ring

that is suspended at the center of the construction The farm is held in place

using three anchors marked with buoys Mussels can be placed along thebottom where they will feed off the fish droppings thereby keeping the area

cleaner

Fish

A large variety of fish can be raised with the SMALL FISHFARM but some areespecially well suited In addition to ones taste and preferences the choice

must depend on the salinity temperature and quality of the water One must

also consider the other organisms that inhabit the water including algae

seaweed plants and other fish species So as to not disturb the trophic systemit is important to use a fish species native to the body of water being considered

Furthermore some species require maintenance and feeding while others - if














eel and many others

Corner fitting







Anchor and buoy


net






Swan mussels

(Anodonta Cygnea)





Common carp

(Cyprinus Carpio)

Nets










Extensions
















store the energy


Maintenance






Component list



27 bakelite knobs

polyethylene foam



3 black buoys


bolts and nuts








Back to manuals

Back to HOME













eel and many others

Corner fitting







Anchor and buoy


net






Swan mussels

(Anodonta Cygnea)





Common carp

(Cyprinus Carpio)

Nets










Extensions
















store the energy


Maintenance






Component list



27 bakelite knobs

polyethylene foam



3 black buoys


bolts and nuts








Back to manuals

Back to HOME





Anchor and buoy


net






Swan mussels

(Anodonta Cygnea)





Common carp

(Cyprinus Carpio)

Nets










Extensions
















store the energy


Maintenance






Component list



27 bakelite knobs

polyethylene foam



3 black buoys


bolts and nuts








Back to manuals

Back to HOME





Swan mussels

(Anodonta Cygnea)





Common carp

(Cyprinus Carpio)

Nets










Extensions
















store the energy


Maintenance






Component list



27 bakelite knobs

polyethylene foam



3 black buoys


bolts and nuts








Back to manuals

Back to HOME




Common carp

(Cyprinus Carpio)

Nets










Extensions
















store the energy


Maintenance






Component list



27 bakelite knobs

polyethylene foam



3 black buoys


bolts and nuts








Back to manuals

Back to HOME







store the energy


Maintenance






Component list



27 bakelite knobs

polyethylene foam



3 black buoys


bolts and nuts








Back to manuals

Back to HOME





Back to manuals

Back to HOME

Manual for SMALL FISHFARM.pdf

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