Definition: Parental care is defined as an association between parents and offspring through which the chance of survival of young ones increases by behaviour performed by parents.
77% of fishes do not show parental care, where 17% of fishes shows care of eggs only and 6% of fishes care for their eggs and newly hatched young.
Parental care in fishes is a diverse and fascinating behaviour, exhibiting a wide range of strategies across different species to ensure the survival of their offspring. Here are some key points:
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Types of Parental Care:
No Care: Many fish species do not provide any care to their offspring, relying instead on producing large numbers of eggs to ensure that some will survive.
External Care: This includes behaviours such as guarding and aerating the eggs. For example, male sticklebacks build nests and protect the eggs until they hatch.
Internal Care: In species like seahorses and pipefish, males carry the eggs in specialized pouches until they hatch.
Brood Care: Some fish, such as cichlids, protect and care for their young after hatching. They may guard the fry, lead them to food sources, and even take them into their mouths for protection.
Pattern and various Methods of Parental Care in fishes:
1. Deposition in suitable places:
A number of fish species depositing their eggs to suitably protected places. They do not build nests.
(i) Deposition of eggs in sticky covering:
In Carps, eggs are usually laid with some special sticky covering attached to each other, or to stores, weeds.
(ii) Elggs scattered over Aquatic plants:
Eggs of fishes such as Pikes (Esoxlucius sp.), Carps etc. are scattered over aquatic plants, sea weeds remain attached.
(iii) Eggs layed at suitable places:
Andromous fishes such as Salmo sp., Acipenser sp. & Oncorhyncus sp. lay their eggs in the pits and cover them.
(iv) Eggs deposited on dead shells of bivalves:
Females of Cyprinid family deposit their eggs on the dead shells of mussels. Females of European bitterling (Rhodeusamarus sp.) deposit eggs in the siphon of fresh water mussel by an ovipositor.
2. Deposition & Eggs into self Made Nest:
Some species of fish prepare different types of nests for safe deposition & protection of eggs.
(i) Circular Nest:
The male Bowfin (Amia calva) prepares a crude-pit like circular nest among aquatic vegetation. The fertilized eggs are then protected by the male.
(ii) Hole/Burrow Nest:
The African lung fish (Protopterus sp.) prepares a simple nest in the form of deep hole to swampy places on riverbank.
(iii) Foamy Nests:
The male fighting fish (Beta sp.) builds a nest by blowing bubbles of air and sticky mucus forming a floating mass of foam on the surface of water.
(iv) Cup Shaped Nest:
The maleApeltsquadracus sp. builds an elaborate cup shaped nest attached to rooted plants close to the bottom.
(v) Floating Nest:
The male Mormyrids (Gymnarchus sp.) made a floating nest by help of aquatic vegetation above water surfaces.
3. Concealing eggs & youngs in or on their body:
Certain species of fishes have developed many structure in their body to safeguard the eggs young ones.
(i) Eggs and Youngs In Mouth Cavity:
In many Cichlids (Tilapia sp.), the female broods the eggs in mouth. In most marine cat fish (Arius sp.) the male carries the eggs and young ones in his mouth. Male not take food at this period.
(ii) Eggs attached to Cephalic hook:
The male nursery fish (Kurtus) of New Guinea, carries the mass of eggs on the forehead, held in cephalic hooks.
(iii) Eggs kept in brood pouches:
In sea horse (Hippocampus sp.) males kept the eggs in brood pouches found in lower surface of abdomen. He provides nutrients and oxygen to fertilized eggs for several weeks.
(iv) Egg Capsules:
In oviparous elasmobranchs such as Shark and Rays, the fertilized eggs are laid inside the Horney egg capsule called ‘Mermaid purse’.
4. Viviparity:
Certain species of fish are viviparous, evolved internal incubation and give birth to young ones.
Example: Teleosts, Gambusia, Shiner perch (Cymatogaster sp.); Nurse Shark (ovo-viviparous) etc.
Parental care in fishes is an adaptive behavior that increases the chances of survival for their offspring in various aquatic environments. The level and type of care provided are influenced by ecological factors, predation pressure, and the evolutionary history of the species.