Shrinkage of Inland Silverside Larvae Preserved in Ethanol and Formalin

Abstract

Length measurements of preserved larval fish are necessary in many types of larval fish surveys. If the fixative causes significant shrinkage, then the preserved lengths cannot be used to indicate accurate live lengths. The objective of this study was to determine how preservation in two different concentrations of formalin and ethanol affects the total length of larval inland silversides Menidia beryllina. Larvae were measured (nearest 0.1 mm) and individually fixed in one of four fixative treatments (80% ethanol, 100% ethanol, 5% buffered formalin, and 10% buffered formalin). Fish were remeasured (nearest 0.1 mm) at 15 min; 4 h; and 1, 7, 14, and 21 d after preservation. Most shrinkage occurred within the first day after preservation in all four fixatives. Initial length was positively correlated with absolute shrinkage, but percent shrinkage was not affected by initial length. We found no difference in percent shrinkage between the 80% and 100% ethanol concentrations. The 10% buffered formalin caused more percent shrinkage than 5% buffered formalin. Furthermore, ethanol (80% and 100% combined) caused greater percent shrinkage than either 5% or 10% buffered formalin.

The Effect of Fixative an Total Length of Small-Bodied Stream Fishes

“…Our results are consistent with those from other studies that indicated greater shrinkage in alcohol for larval fish (Fisher et al 1998, Cunningham et al 2000. Similarly, Distefano et al (1994) found preservative had no effect on the percentage of change in the overall length of central stoneroller (Campostoma anomalurn) after 90 and 180 day intervals.…”

“…Ethyl alcohol causes greater reduction in preserved larval fish length than forinalin (Kruse and Dalley 1990. Fisher et al 1998, Cunningham et al 2000, Moku et al 2004 were collected from the Kansas River, Riley County Kansas on 10 November 2005. The fish were visually sorted to obtain samples of similar total lengths (measured to the nearest millimeter), and then were placed into individually numbered sample bags containing 100 ml of one of the fixative solutions (5% and 10% formalin and 70% and 95% ethyl alcohol).…”

Morphological development and allometric growth of yellowtail kingfishSeriola lalandiV. larvae under culture conditions

“…To minimize the effect of shrinkage due to the fixation process, samples were analysed within 1 month after fixing (Fisher, Anderson & Willis 1998;Cunningham, Granberry & Pope 2000). Thereafter and until 45 dph, larvae were sample every 5 days.…”

Change in body size of juvenile marbled sole Pseudopleuronectes yokohamae after preservation in ethanol

“…Inaccurate measurements of body length and body weight are likely to cause errors in estimation of biological Morkert and Bergstedt 1990;Oozeki et al 1991;Fisher et al 1998;Smith and Walker 2003). However, the extent of shrinkage differs among fish species, developmental stages, and different kinds and/or concentrations of preservatives (e.g., Hay 1982; Leslie and Moore 1986;Kruse and Dalley 1990;Cunningham et al 2000;Moku et al 2004).…”