An 8-week feeding trial was conducted to investigate the effects of replacing fishmeal with defatted black soldier fly larvae meal (DBSFLM) in the diets of Japanese eel on their growth performance, fillet texture, serum biochemical parameters, and intestinal histomorphology. Six isoproteic (520 g kg⁻¹), isolipidic (80 g kg⁻¹), and isoenergetic (15 MJ kg⁻¹) diets were formulated with fishmeal replacement levels of 0% (R0), 15% (R15), 30% (R30), 45% (R45), 60% (R60), and 75% (R75). The growth performance, feed utilization efficiency, survival rate, serum liver function enzymes, antioxidant ability, and lysozyme activity of fish were not affected ( ) by DBSFLM. However, the crude protein and cohesiveness of the fillet in groups R60 and R75 significantly decreased, and the fillet hardness significantly increased ( ). Additionally, the intestinal villus length significantly decreased in the R75 group, and the goblet cell densities were significantly lower in the R45, R60, and R75 groups ( ). Overall, high levels of DBSFLM did not affect growth performance and serum biochemical parameters but significantly altered fillet proximate composition and texture and intestinal histomorphology ( ). The optimal fishmeal replacement level is 30% with 184 g kg⁻¹ DBSFLM.

Floating photovoltaic arrays on ponds may alter thermal and optical conditions that are relevant to aquaculture performance. This study compared 0% and 40% surface shading in two outdoor earthen-pond trials, one with Asian sea bass (Lates calcarifer) and one with Japanese sea bass (Lateolabrax japonicus). Temperature was logged hourly and summarized as daily means; water quality was sampled biweekly; fish were measured repeatedly, with endpoint growth compared within species. The result shows that shading lowered pond temperature and the diurnal temperature range and reduced the number of days above species benchmark temperatures. Indicators associated with phytoplankton, including suspended solids and chlorophyll a, were lower under shading, whereas dissolved inorganic nutrients were higher. In the Japanese sea bass trial, dissolved oxygen was higher without shading. Final body weight did not differ between treatments within either trial, but survival was higher with 40% shading. Principal component analysis and permutational multivariate analysis of variance indicated a treatment signal in multivariate water quality. Because the trials occurred in different years with one pond per treatment, inference was restricted to contrasts within each species. Overall, moderate surface shading cooled ponds and altered water quality without reducing growth.

Interleukin 1-beta (IL-1B) is a key proinflammatory cytokine involved in disease resistance. In recent years, il-1β genes from several teleosts have been cloned. The Japanese eel (Anguilla japonica) is an evolutionarily primitive fish widely farmed in East Asia. The il-1β gene has not yet been cloned from Japanese eel. In this study, the complete cDNA of il-1β was successfully sequenced from peripheral leukocytes through the rapid amplification of cDNA ends. The il-1β gene consists of five exons and four introns, and the full-length cDNA spans 1204 bp, comprising a 99-bp 5' untranslated region, a 750-bp coding sequence, and a 355-bp 3' untranslated region. The deduced amino acid sequence includes a consensus IL-1 family signature but lacks both a signal peptide and an IL-1 converting enzyme cleavage site, similar to other teleost IL-1B proteins. Homology analysis revealed that Japanese eel IL-1B is highly conserved within the order Anguilliformes, sharing the highest similarity with American eel (Anguilla rostrata), followed by conger eel (Conger myriaster). Tissue expression analysis showed that il-1β is constitutively expressed in multiple tissues, with high expression in peripheral leukocytes and the spleen; moderate expression in the gill, liver, head kidney, trunk kidney, and intestine; and low expression in the heart, stomach, skin, and muscle. In vitro stimulation with zymosan, polyinosinic-polycytidylic acid, and lipopolysaccharide upregulated il-1β expression in peripheral leukocytes.