Good and bad classification of stinging catfish ( Heteropneustes fossilis).

Good quality stinging catfish Eyes clear and bulging Skin shiny with natural slime Flesh firm and elastic Gills bright red or pink Fresh, mild fishy smell No discoloration or spots Active movement if live Bad quality stinging catfish Eyes sunken and cloudy Skin dull, sticky, excess slime Flesh soft, leaves finger mark Gills brown, grey, or black Strong foul or ammonia smell Presence of spots, wounds, or parasites Lethargic or dead for long time Conclusion Good fish is fresh, firm, and odorless. Bad fish shows spoilage signs and is unsafe for consumption.优质刺鲶鱼（stinging catfish） 眼睛清澈饱满 体表带有天然黏液且富有光泽 肉质紧实且富有弹性 鳃部呈亮红色或粉红色 带有清新温和的鱼腥味 无变色或斑点 活体状态下活动活跃 劣质刺鲶鱼 眼睛凹陷且浑浊 体表黯淡发黏、黏液过量 肉质松软，按压后会留下指痕 鳃部呈褐色、灰色或黑色 带有强烈腐臭或氨味 存在斑点、伤口或寄生虫 行动迟缓或已死亡较长时间 结论 优质鱼类新鲜紧实、无异味。劣质鱼类存在腐败变质迹象，不可供食用。