Principle of Fish Nutrition

• Carbohydrate Utilization Across Feeding Guilds:
• Herbivorous Fishes (e.g., Grass Carp Ctenopharyngodon idella): Possess elongated gastrointestinal tracts (high relative gut length, RGL $\gt 2-3$) and secrete high levels of endogenous and symbiotic microbial amylases and maltases.
• They can efficiently digest, absorb, and metabolize high dietary carbohydrate levels ($30\% - 45\%$) as energy sources compared to carnivorous fishes.
• Correct Option: Option 1 (Herbivorous fishes).

• Carbohydrate Intolerance in Carnivorous Fishes:
• Carnivorous fishes (such as trout, salmon, sea bass, groupers) exhibit poor dietary carbohydrate utilization and prolonged post-prandial hyperglycemia.
• Key Factors:

• Low synthesis and secretion of digestive $\alpha$-amylase in the pancreas and intestinal mucosa.
• Low activity of hepatic hexokinase and glucokinase, limiting glucose phosphorylation and hepatic glycolytic flux.
  • Correct Option: Option 1 (Low amylase).

• Carbohydrates: Carbohydrates are polyhydroxy aldehydes or ketones, or substances that yield these compounds upon hydrolysis. They are organic compounds containing carbon, hydrogen, and oxygen, generally in a ratio of $1:2:1$ with the empirical formula $(CH_2O)_n$.
• High Molecular Weight Polysaccharides: Complex carbohydrates (such as starch, glycogen, cellulose, and chitin) are macromolecules of high molecular weight composed of numerous repeating monosaccharide units linked by glycosidic bonds.
• nalysis:
• (Organic compounds of high molecular weight): Correct. Carbohydrates represent a major class of biological organic macromolecules.
• (Triglycerides where glycerol is esterified): Incorrect. This defines lipids/triacylglycerols, not carbohydrates.
• (Inorganic compounds of high molecular weight): Incorrect. Carbohydrates are carbon-based organic compounds, not inorganic.
• (All statements are true): Incorrect.

Correct option: (1) Organic compounds of high molecular weight