ICAR AIEEA PG 2024 - Fisheries Science

In Dipnoi (lungfishes) and Holocephali (chimaeras / ratfishes), the caudal fin is Diphycercal (symmetrical externally and internally, where the vertebral column extends straight back to the tip of the tail, dividing the fin symmetrically into epichordal and hypochordal lobes).

Both statements are correct biological facts of parental care and brood symbiosis in fishes:
Statement (I) is correct: Female European bitterling (taxonomically recognized as Rhodeus amarus; historically grouped under Rhodeus sericeus) possesses a long ovipositor to deposit fertilized eggs directly inside the gill/mantle cavity of unionid freshwater mussels (Anodonta or Unio).
Statement (II) is correct: Snailfish (Careproctus spp.) use a specialized ovipositor to deposit egg masses inside the branchial chamber beneath the protective carapace of lithodid king crabs.

Both statements are scientifically true:
Prolactin is often designated the 'freshwater-adapting hormone' in euryhaline and migratory teleosts, acting antagonistically to cortisol/growth hormone (seawater adaptors).
In freshwater, fishes face continuous passive osmotic water inflow; prolactin increases glomerular filtration rate (GFR) and suppresses tubular water reabsorption, enabling the copious production and excretion of highly dilute urine while promoting branchial ion retention.