Chemical cues and pheromones mediate fish reproduction, aggregation, risk assessment, and kin recognition. To better understand the chemical communication of conspecific fish, the behavioral responses to bile acids (BAs), their source, and reception investigated in large yellow croaker (Larimichthys crocea). Behavioral experimental results indicated that juvenile fish were attracted to intestinal contents (ICs) emanating from conspecifics, regardless of whether the fish were feeding. IC BA-targeted metabolomics revealed that cholic acid (CA), taurocholic acid (TCA), taurochenodeoxycholic acid (TCDCA), chenodeoxycholic acid (CDCA), and taurodeoxycholic acid (TDCA) were the top five categories. Tests with and without fasting yielded similar categories and proportions of BAs, indicating that the intestinal BA profiles were generally stable. At the nanomolar level, CA led to significant preference behavior (p < 0.01). The electrophysiological results supported the hypothesis that the top five BAs were potent odorants in L. crocea. Moreover, inhibition of adenylate cyclase–cyclic adenosine monophosphate (AC–cAMP) signaling and phospholipase C (PLC) signaling reduced the electro-olfactogram (EOG) responses to CA and CDCA. Collectively, the findings of this study indicate that conspecific individuals could be attracted by ICs unrelated to feeding. As a key intestinal BA, CA led to fish preference behaviors and olfactory responses relying on cAMP and PLC transduction cascades.

Optimizing bile acids (BAs) inclusion in commercial diets and understanding its molecular mechanisms in Pacific white shrimp ( Litopenaeus vannamei ) are crucial for improving growth performance. The present study investigated the effect of dietary BAs on shrimp growth and metabolic mechanisms using multiomics approaches. A total of 1800 shrimp (0.16 ± 0.01 g) were fed six diets with BAs levels: 0 mg kg ⁻¹ (control, BA0), 50 mg kg ⁻¹ (BA1), 100 mg kg ⁻¹ (BA2), 150 mg kg ⁻¹ (BA3), 200 mg kg ⁻¹ (BA4), and 250 mg kg ⁻¹ (BA5). After 56 days, the growth performance of BA4 and BA5 groups was significantly higher than the BA0, BA1, and BA2 groups. Regression analysis indicated an optimal dietary BAs level of 216−218 mg kg ⁻¹ . Biochemical analysis showed that the BA4 group significantly reduced crude lipid content, triglycerides, and nonesterified fatty acids, while increasing digestive enzyme activities. RNA‐seq revealed reduced expression of lipid synthesis genes ( srebp1 , fasn , scd , etc.), while enhancing the expression of genes related to lipid catabolism ( acox1 , angpt4 , dip13a , and gba ) and digestive enzymes ( prss1 and prss2 ). Metabolomic analysis showed taurine‐conjugated BAs as predominant, with taurine content decreasing likely due to its conjugation with BAs and loss in feces. These results suggest that the optimal BAs level of 216−218 mg kg ⁻¹ improved shrimp growth and lipid metabolism by enhancing nutrient digestion, promoting lipolysis, and inhibiting lipid synthesis, without altering the BAs pool balance. This study first revealed taurine’s critical role in Pacific white shrimp BAs metabolism.

Olfactory communication plays a critical role in fish behavior and physiology, particularly in environments where visual and auditory signals are constrained. Bile acids, dual-function molecules serving as digestive agents and olfactory signals, are potent olfactory cues in aquatic ecosystems. The present study investigated the role of ursodeoxycholic acid (UDCA) as an olfactory attractant in large yellow croaker (Larimichthys crocea), an endangered species. Electrophysiological recordings demonstrated that UDCA elicits strong, concentration-dependent olfactory responses with a detection threshold of 10−12 mol l−1. Behavioral assays revealed UDCA-induced attraction exceeding that of other structurally similar bile acids, demonstrating significantly higher potency (P<0.05). Transcriptome analysis and pharmacological treatments revealed functional associations in UDCA detection. V2R1 upregulation and PLC pathway engagement (day 3) preceded delayed induction of OR11A1, TAAR13C-10 and OR52L2 with cAMP signaling (day 7), suggesting phased receptor involvement. Functional receptor expression assays confirmed that V2R1 mediates UDCA-induced calcium signaling, whereas OR11A1, TAAR13C-10 and OR52L2 respond through cAMP signaling. The present study provides a comprehensive understanding of UDCA chemosensation, linking receptor function, signaling pathways and behavioral responses. These findings enhance our understanding of fish olfactory systems and offer potential applications for species conservation and sustainable fisheries management.