The Effect of Fixation, Preservation and Freezing on Certain Body Proportions of Two Small Pelagic Fish Species, Sardinella Longiceps (Family: Clupeidae) and Selaroides Leptolepis Collected From Muscat Waters, Sultanate of Oman - page 5

 

 

S. longiceps, the greatest incremental change in body measurements was noticed in specimens fixed in 10% formaldehyde mixed with tap water (13.3%) while the least incremental change was observed in fish specimens put in 10% formaldehyde mixed with distilled water (1.5%).

For S. leptolepis, the greatest incremental change in body lengths was noticed in specimens put in 5% formaldehyde mixed with tap water (24.3%) while the least incremental change was in specimens fixed in 10% formaldehyde mixed with tap water. The greatest shrinkage was noticed in specimens preserved in 70% ethanol mixed with tap water (6.7%) while least shrinkage was in fish fixed in 10% formaldehyde mixed with distilled water. No detectable effects were noticed in fish specimens put in 10% formaldehyde mixed with tap water (1.4%), 10% formaldehyde mixed with distilled water (0.8%) and 5% formaldehyde mixed with tap water.

Wide variations in the response of different fish body proportions to different concentrations of fixatives and preservatives on one side and freezing effect on the other have been observed (Figures 8-14). In S. longiceps, total length showed slight variation in different fixatives and preservatives except for formaldehyde 10% mixed with tap water and ethanol 70% mixed with distilled water. In the latter solutions, wide variations were observed in the first nine weeks. During our experiment, total length showed no effect for at least 11-12 week period. The increases in total length that occurred in the case of preservation with 70% ethanol mixed with distilled water were significant.

 

Figure 8: Effect of formaldehyde 10% -tap water on different body proportions of Selaroides leptolepis.

 

Figure 9: Effect of formaldehyde 10% -distilled water on different body proportions of Selaroides leptolepis.

 

Figure 10: Effect of formaldehyde 5% -tap water on different body proportions of Selaroides leptolepis.