Correction of the weight and length for juveniles Atherinella brasiliensis (Actinopterygii: Atherinopsidae) after fixation in formalin and preservation in ethanol

Abstract

The present study compared losses of weight and length in specimens of Atherinella brasiliensis (Quoy & Gaimard, 1825) after fixation in formalin 10% during ten days, and posterior preservation in ethanol 70% for 45 days, in two solvents: freshwater and marine water. Additionally, correction factors were proposed to calculate the correction for weight and length from preserved specimens. The specimens were weighted and measured after collection (fresh), and with 10, 20, 27, 34, 41 and 55 days of fixation plus preservation. The largest losses in weight occurred during the first 20 days (10.35 ± 0.31% - freshwater; 11.29 ± 0.44% - marine water), continuing with lesser intensity up to the 27th day in freshwater dilution, and up to the 34th day in marine water dilution. Weight losses stabilized by the 34th day for both freshwater (11.77 ± 0.33%) and marine water (13.62 ± 0.41%). The largest losses in the total length for the two methods were also observed in the first 20 days (7.42 ± 0.27% - freshwater; 9.76 ± 0.26 - marine water), stabilizing after the 27th day in freshwater (8.60 ± 0.26%) and 20th day in marine water (9.76 ± 0.26%). The losses of weight and total length were significantly dependent on fish size, with smaller individuals suffering the most significant losses. Complete regression equations were proposed for the retro-calculation of fresh weight and total length from the preserved specimens for freshwater (Wfresh = 1.0536W P + 0.0416; TLfresh = 0.9588TL P + 5.8437) and marine water (Wfresh = 1.0868W P + 0.0451; TLfresh = 0.8621TL P + 10.425)

Embryonic development of lake whitefish Coregonus clupeaformis: a staging series, analysis of growth and effects of fixation

“…By presenting multiple staging methods and descriptions of development, additional tools are provided to researchers that complement morphological stages. A common practice in embryo studies involves preserving samples in fixatives such as ethanol or formaldehyde; which have been reported to cause embryo shrinkage (Melo et al ., ; Vergara‐Solana et al ., ). This study presents the effects of two common fixatives, ethanol and formalin, on embryo morphometrics to assist researchers in both the staging and use of embryos for morphological measurements following fixation.…”

“…Several studies have investigated the combined effects of formalin and ethanol on species of fishes post hatch. Other studies have reported similar embryo shrinkage trends (Melo et al ., ; Vergara‐Solana et al ., ). The change in L T from fixed (10% formalin followed by 70% ethanol) to unfixed individuals has been found to range from 5·7% in golden mojarra Deckertichthys aureolus (Jordan & Gilbert 1882) (Vergara‐Solana et al ., ) to 11·77% in juvenile Brazilian silverside Atherinella brasiliensis (Quoy & Gaimard 1825) (Melo et al ., ).…”

Does diet variation determine the digestive tract length of Capoeta banarescui Turan, Kottelat, Ekmekci and Imamoglu, 2006?

“…Captured specimens were anaesthetized with MS 222 and preserved in 10% formalin, then transferred to the Department of Fisheries and Aquaculture (Gaziosmanpasa University, Turkey). The largest losses in weight and length due to formalin are known to occur during the first three weeks, and then begin to stabilize after about six weeks (Melo et al., ). All specimens from each location were affected by formalin in a same manner.…”

Oscillation of an Anuran Hybrid Zone: Morphological Evidence Spanning 50 Years

“…To do this, we re-photographed 13 specimens retained as vouchers after they had been preserved in ethanol after four months and again after four years. Since body length has been shown to stabilize after less than two months of preservation [23], [24], [25], we considered four months to be adequate time in preservative to observe an effect and four years enough time to test if the shrinkage had stabilized. In line with these previous studies, we expected some characters, such as SVL, to shrink significantly in preservative and others, such as features of the bony cranial crests, to show little, if any, change [22].…”