Evaluations of the efficacy of Hypersaturated Saline Solutions for the preservation of fish and amphibians for educational purposes

Abstract

Fish and amphibians are traditionally preserved in formalin or ethyl alcohol, but these fluids can compromise their morphological characteristics. Hypersaturated saline solutions, already used in veterinary medicine, have emerged as effective preservation alternatives, maintaining the appearance of specimens similar to that of living organisms. This study evaluated the efficacy of hypersaturated saline solutions (26% and 30%) for the preservation of fish and tadpoles (Anura) as teaching materials, comparing them with conventional techniques, such as 10% formalin and 70% ethyl alcohol, in addition to the use of 20% curing salt. Treatments with 20% curing salt and 26% or 30% saline solutions (T3 and T4) showed good morphological results, preserving colors and malleability similar to those of living animals, but presented bacterial and fungal growth, leading to decomposition after 8 months. Treatments T1 and T2, with prior fixation in 10% formalin and preservation in hypersaturated saline solution, were more effective, maintaining morphological quality for more than five years without microbial growth. Preservation in 30% hypersaturated saline solution, preceded by fixation in formalin, proved to be the most effective and low-cost method for educational purposes, preserving morphological characteristics and with antiseptic properties.