Housing, Husbandry, and Clinical Techniques for Crayfish (Procambarus clarkii) used in Biomedical Research

Abstract Crayfish (Decapoda: Astacoidea & Parastacoidea), are amongst the few animals that have stem cells within hemolymph, with the capacity to continuously produce differentiated neuronal structures throughout life. As crayfish and other invertebrates continue to become common models in research to study human disease, it is vital that we develop universal laboratory standards and guidelines on housing and husbandry practices. This publication presents introductory data on housing, husbandry, hemolymph collection and statistically supported anesthesia trials, to support future research endeavors. Evaluation of housing, husbandry, clinical and anesthetic techniques in Procambarus clarkii maintained in a biomedical research setting were performed. An option for hemolymph collection, in the area termed, the Ventral Coelomic Hemolymph Collection Zone (VCHCZ) is presented as a technique to assess hemocytes. Additionally, Wright Giemsa stained slides of crayfish hemolymph were evaluated by a board-certified veterinary clinical pathologist for interpretation and confirmation of hemolymph collection. The housing and husbandry experiments were performed over a duration of 37 days. Mortality rates and physical health assessments were performed. The following water quality parameters were concurrently evaluated: temperature, light cycle, pH, KH, GH, conductivity, total dissolved solids, salinity, ammonia, nitrite, and nitrate. Anesthetic techniques were evaluated between four experimental groups: (A) immersion in buffered MS-222 (50 mg/L), (B) immersion in buffered MS-222 (150 mg/L) (C) immersion in Propofol (65 mg/L) and (D) Propofol injection (100 mg/kg) into VCHCZ. Housing and husbandry techniques were validated with 0% mortality and normal species-specific behaviors were observed. MS-222 immersion had no observable effect on crayfish. Propofol immersion (65 mg/L) created sedative effects allowing for appropriate handling. Propofol injection (100 mg/kg) into VCHCZ successfully created a deep anesthetic plane that would allow for more invasive or surgical procedures, without adverse effects during or after recovery.