Intraperitoneal injection into adult zebrafish.

Area of Science:

• Aquatic animal research
• Zebrafish models
• Animal physiology

Background:

• Chemical treatment of zebrafish often involves tank water immersion, making accurate reagent uptake per fish difficult.
• Metabolic studies require precise reagent delivery based on individual fish weight, which tank immersion cannot provide.

Purpose of the Study:

• To present a novel method for intraperitoneal (IP) injection in adult zebrafish.
• To establish a safe and reliable technique for delivering defined reagent quantities to individual fish.

Main Methods:

• Adapted veterinary IP injection techniques for adult zebrafish.
• Implemented gentle handling protocols, including fasting, weighing, anesthesia, and recovery.
• Utilized a small injection volume (35G needle) and Cortland salt solution as a vehicle.
• Ensured gill aeration during anesthesia and injection using a water-saturated sponge trough.

Main Results:

• The IP injection procedure demonstrated zero mortality and minimal, brief bleeding in 5/127 injections.
• Demonstrated utility by injecting glucose and monitoring blood glucose levels, showing a transient rise and return to baseline.
• Vehicle-injected and non-injected fish showed no significant difference in blood glucose, indicating the procedure does not induce a stress response.

Conclusions:

• Intraperitoneal injection is a safe and effective method for delivering precise reagent doses to adult zebrafish.
• This technique is suitable for metabolic studies and other research requiring controlled substance delivery.
• The procedure minimizes stress and does not significantly alter physiological parameters like blood glucose levels.