EXPERIMENTAL TECHNIQUES (cont)
Intramuscular injections can be given just below the dorsal fin or midway between the dorsal fin and lateral line A 20-23 gauge needle is used commonly in larger laboratory fish. The syringe must be aspirated after the needle is inserted to assure that it is not in a blood vessel. If the needle is in a vessel blood will enter the syringe. If this happens the needle should be slightly repositioned and checked again by aspiration.
IM injection in the fish