Netting a Fish

Netting fish is important for both health assessments and treatments and will vary depending on the location number and species of the specimen. Typically the coloring of the net will be clear or blue to reduce aversion by the fish and will be composed of a tough but flexible polymer like nylon. Also to prevent the transmission of diseases between tanks, nets should be sterilized using an alcohol solution before use.

Number:

o If one specific individual is desired then two handheld nets (directly proportional to body size) are the best option as the target is often sick or inhibited in some aspect. Place the two nets apart and gently use one net to guide the fish into the other. The same procedure can be used for the isolation of a random individual for quality control etc.

o If several or all specimens are required, a large enclosing net can be used with a pully. The net is initially rolled through the bottom of the tank for the desired number of fish and then pulled up.

Species:

o Typically more support is given to the fish with the use of a finer mesh thus reducing stress. However this can be a problem with species such as catfish that have reflex barbs, which become entangled in finer mesh. Therefore the fineness of the mesh will vary to accommodate different species e.g. finer meshes are typically used on salmonidae species.

When setting up an isolation tank the following characteristics are ideal for the observation and recovery of a fish:

o Lengthwise should be from 3-5 of the length of the fish with proportional length and width.

o A canister filter is ideal to provide filtration and aeration for larger tanks and hang-on filters are suitable for smaller ones. Also a new cartridge should be used for every new inhabitant

o The tank should be bare to prevent the accumulation of contaminants such as uneaten food and waste in substrate.

o There should be a switch lighting to provide interrogation light but only when under observation.

o An airstone is helpful as highly oxygenated water reduces stress.

o A heater is necessary if the species is tropical or can be used to maintain a stable temperature for sick and therefore weaker fish.

o The fish should not be fed unless necessary.