Aquaculture America 2024

February 18 - 21, 2024

San Antonio, Texas

ADVANCED IMAGING TO UNRAVEL SKELETAL DEFORMITIES IN AQUACULTURED MARINE AQUARIUM FISH

Abby Grove*, Allex N. Gourlay, Lena R. Fitzgerald, Ryan Rubino, Shubham K.   Mathur, Andrew L. Rhyne

 

Center for Economic and Environmental Development

 Roger Williams University

One Old Ferry Rd

Bristol, RI 02809

agrove458@g.rwu.edu

 



Deformities in aquacultured fish pose production challenges, particularly in marine aquarium  aquaculture. H ead, spine, gill, and swim bladder deformities repeatably occur impacting the marketability of fish . To study the extent of the abnormality, a method of preserving and imaging must be developed.   We have noticed that previous methods of euthanasia  can  cause stress, leading to exaggerations in features such as flared operculum, open mouths, and body curvature due to rigor mortis . When  investigating the nature of craniofacial deformity, it is vital that the deformed features are not exaggerated  during  the euthanasia and fixing procedure .

Fine scale imaging via computerized tomography (CT) requires specimens to be positioned well, and ideally with each specimen in the same position for comparison. The easiest way to scan most preserved samples is through embedding in agars or resins.  A gar e mbedding techniques are traditionally utilized on larval fish, embryos, and histological tissue sections to aid in image capture .  This work, however, focuses on model species, that differ in size and application  to  marine aquarium fishes. There has been little to no research or protocols available for emending full fish for craniofacial analysis. 

B

C

During this study  multiple methods of euthanasia, fixing, and agar embedding will be compared to find the  best method for image analysis of specimens.  Species aquacultured including clownfish (Amphiprion ocellaris), royal gramma ( Gramma lorteo), smallmouth grunt (Haemulon chrysargyreum), glassy sweeper (Pempheris schomburgkii), and the Atlantic lookdown (Selene vomer) will be utilized .

Fish representatives with mild (Figure 1A), moderate (Figure 1B ), and extreme (Figure 1C )  craniofacial deformities will be  euthanized in  Tricaine methanesulfonate (MS-222)  in increments of 50 ppm  buffered with  100 ppm  sodium bicarbonate  and  fixed in 10% neutral buffered formalin . This procedure will result in natural, relaxed fish for imaging. The fixed fish will then be embedded in 1-2% agar at temperatures ranging from 30ºC to 50º C. M ethod  development will determine the best viscosity and temperature to allow ample time to manipulate the specimen and remove bubbles before setting. Consistent, clear, bubble-free embedded specimens can then be scanned to examine the craniofacial features of the fish with increased accuracy.