Fruits and vegetables are wasted in huge amounts and nearly 30% of all produced food is never consumed which leads to many economic and environmental issues. Similarly, the poultry industry generates a huge volume of waste. This refuse is reported to have high nutritional value and could be used as ingredients in the feed industry. Black soldier flies,Hermetia illucens, are potentially capable of converting different organic wastes into protein-rich biomass and considered as a viable alternative protein source to partially substitute fish meal used in aquafeeds, thereby contributing to the sustainability of aquaculture. In this study, the effect of two different organic waste substrates and their mixture, namely chicken waste meal (C), fruit & vegetable waste (FV), and a combination (1:9) of chicken waste meal and fruit & vegetable waste (M) on the nutritional content of black soldier fly prepupae (BSFP) was investigated. Significant differences were observed in energy content and proximate composition of the substrates which significantly altered the energy content and nutritional composition of the BSFP. BSFP reared on FV were low in crude protein, crude lipid and high in crude carbohydrate compared to BSFP reared on C and M. The amino acid contents of BSFP were characterised by high levels of lysine, leucine, and valine. Significant differences were detected between BSFP groups in terms of amino acid content. The fatty acid composition of the BSFP were dominated by the saturated fatty acids (SFA) ranging between 41.8±0.10% (M) and 67.11±0.08% (C). M-fed BSFP had significantly higher SFA, monosaturated fatty acid (MUFA), and polyunsaturated fatty acid (PUFA) compositions than C- and FV-fed BSFP. M-fed BSFP had a high C18:1n9 (17.01±0.02%), C16:0 (17.02±0.09%), C18:2n-6 (14.63±0.02%), and C12:0 (15.19%) fatty acid composition. The fatty acid profile of the C-fed BSFP was characterised by high levels of C14:0 (28.16±0.11%), C12:0 (25.79±0.09%), and C18:1n-9 (13.41±0.03%), whereas FV-fed BSFP was characterised by high levels of C16:0 (19.33±0.08%), C12:0 (16.64±0.18%), and C18:1n-9 (12.51±0.04%). Our results demonstrated that chicken waste meal, fruit & vegetables waste, and their mixture can be used to feed BSFP for sustainable production. However, M-fed BSFP could be used to partially substitute fish meal in carnivorous fish feeds for having a substantially greater nutritional value than BSFP reared on other wastes and for its similarity to fish meal in terms of amino acid content.

Bisphenol A (BPA), an important component of the plastics industry, is characterized as an endocrine disrupting toxic substance for aquatic organisms. This study focused on the toxic effects of BPA on endangered Danube sturgeon larvae (Acipenser gueldenstaedtii). In the study, LC50 values for five different BPA concentrations (100, 200, 400, 800, 1200 μg/L) were observed as 803.4 μg/L, 63.1 μg/L, and 39.6 μg/L at 24th, 48th a nd 72nd hours, respectively. Especially, the lethal effect of BPA on the larvae was remarkable after the 24th hour. On the other hand, histopathological changes were examined based on the LC50 value at the 24th hour. Vacuolization symptom was noted in the gills of the larvae. In addition, vacuolization and melanomacrophage centers caused a severe degradation in liver and kidney tissues of BPA group. In the intestine, the number of goblet cells per ville was lower in the BPA group. As a result, it has been proven by LC50 and histopathological studies that BPA has high toxicity in A. gueldenstaedtii larvae.

Danube sturgeon (Acipenser gueldenstaedtii) which is identified as endangered species can be exposed to pollutants such as bisphenol A (BPA) that have a disruptive effect on the endocrine system at any time. Starting from this motivation, the current study focused on BPA toxicity in A. gueldenstaedtii juvenile individuals and its adverse effects in sub-lethal concentration. The median lethal concentration (LC₅₀) of BPA was 5.03 mg/L in 96th hour. In the chronic period, 0.625 mg/L and 1.25 mg/L BPA concentrations were evaluated based on the result of acute study. Accordingly, growth performance was significantly decreased in BPA groups (1.25 mg/L BPA group was significantly lowest) compared to control (p < 0.05). In the acute period, behavioral disorders were standing at the bottom/corner of tank, slowing and stopping of gill movement, decreased response to stimuli, and death, respectively. While vacuolization was severe in the liver tissue of the fish in the acute period, intense necrosis and melanomacrophage centers were observed in the chronic period. In terms of genotoxicity, longer DNA migration was observed in all groups exposed to BPA than in the control group. In addition, lower erythrocyte and hemoglobin were observed in the BPA groups compared to control. As a result, the current study revealed toxic effect of BPA on A. gueldenstaedtii juvenile individuals and its negative results on fish physiology.