If you are growing fish in aquaponics you will probably have to handle them at one point or another. Keep in mind that it’s never good for the fish to be caught. It represents a serious source of stress but in this article we will see how to minimize the stress and the risk for the fish health.
Don’t feed the day before
When fed, the fish are consuming oxygen and energy to digest. They are way more sensitive and will hardly recover after stress. If you plan to catch and handle your fish, it is very important to not feed them the day before.
Use fish friendly nets
The skin of some fish is covered by scales and the scales are covered by a mucus. Scales and mucus allow the fish to slide into the water but it’s also a real barrier against disease. When handling the fish we must remain aware and avoid removing the mucus and scales. If you use a net to catch your fish, make sure the mesh is not to rough and will not remove the scales and slime. There are different net qualities and you should choose a soft net qualified as “Fish friendly”.
Capillarity is a strength that attract the water from a wet area to a dry area. When you handle fish with dry hands, the moisture from the surface of the fish may be “absorbed” by your dry hands and the scales of the fish may completely stuck to your hands. It would leave the fish with a whole area without scales and leave the door open for disease. To avoid this problem, always wet your hands before touching the fish.
Never touch the gills!!
When handling a dead fish, one of the easiest way to hold it is to put your fingers through the gills, it will give you a nice grip and avoid the fish to slide between your hands. Be careful though, some predators have sharp gills that will cut your skin like razors.
Never use this technique on a live fish! The fish gills are an extremely sensible organ. It is the equivalent to our lungs. The blood is pumped though very fine vessels that allow the gas such as CO2 and NH3 to get out and the O2 to come in. if you handle the fish by the gills you will certainly damage some vessels and the fish will slowly lose their blood and die.
Watch out for the quick move…
I will not teach you anything by saying that the fish don’t like to be kept out of the water. When you catch the fish, they become very agitated as they try to escape and after few seconds they may become tired and very quiet. This is generally the best time to get the fish close to you and examine them. Be careful as very often the fish will unexpectedly start to move again. At this specific time they may slide off your hands and finish on the floor. A fall from a meter or more on a dry floor can terribly injure the fish. The internal bladder can explode or other organs can be damaged and the fish can die. The best thing to do is to handle your fish in a bucket or to dispose a special mat on the floor and limit the lifting high to prevent a dangerous fall.
Welcome here! If you are new, you will probably be interested to discover Jonathan’s six steps to build and manage an Aquaponics system. Click here to access for free! Thanks and good reading 🙂