• Central Control of Fish Appetite:
• Orexigenic Factors (Appetite Stimulants):
• Neuropeptide Y (NPY): Most potent appetite stimulator in fish.
• Galanin, Apelin, AgRP, and Ghrelin: Stimulate feed search and voluntary ingestion.
• Anorexigenic Factors (Satiety / Appetite Suppressants):
• Amylin (Islet Amyloid Polypeptide): A 37-amino-acid peptide co-secreted with insulin by pancreatic $\beta$-cells following feeding.
• Amylin acts centrally in the hypothalamus and hindbrain to inhibit food intake and delay gastric emptying (anorexigenic).
• Other anorexigenic peptides include CCK, CART, Leptin, and $\alpha$-MSH.
• nalysis:
• (Amylin): Correct (it is anorexigenic, not orexigenic).

Correct option: (3) Amylin

• Origin and Nomenclature of C-Reactive Protein:
• Discovered in 1930 by Tillett and Francis, CRP is a prototypical acute-phase pentraxin protein of the innate immune system present in vertebrates, including fishes.
• It was originally named for its ability to form a precipitate in the presence of $Ca^{2+}$ with the "Fraction C" polysaccharide (C-substance, a teichoic acid) extracted from the cell wall of Streptococcus pneumoniae.
• Subsequent biochemical research revealed that CRP specifically binds to the phosphocholine (phosphorylcholine / phosphatidylcholine) headgroup of this C-polysaccharide and exposed cell membrane phospholipids.
• nalysis:
• (Phosphatidylcholine / Phosphocholine): Correct.

Correct option: (4) Phosphatidylcholine

• Primary Endocrine Stress Response:
• In teleosts, acute stress triggers activation of the Hypothalamic-Pituitary-Interrenal (HPI) axis: hypothalamic CRH stimulates pituitary ACTH release, triggering the interrenal tissue to synthesize and secrete cortisol.
• Basal vs Stressed Titer:
• Basal resting levels in undisturbed teleosts: $\lt 5 - 10\text{ ng/ml}$.
• Following acute stress exposure (netting, crowding, confinement), plasma cortisol elevates rapidly, typically peaking within $30 - 120\text{ minutes}$ in the range of $30 - 300\text{ ng/ml}$ (commonly $50 - 200\text{ ng/ml}$ in salmonids, carps, and bass).
• nalysis:
• (30-300 ng/ml): Correct standard physiological acute range.

Correct option: (3) 30-300 ng/ml