What is the feeding habit of fish?...........(Food and Feeding Habits of Finfishes)

 

Food and Feeding Habits of Finfishes

Classification of Organisms Based on Food Production

• Autotrophs: Organisms that make their own food (e.g., plants).
• Heterotrophs: Organisms that do not make their own food and rely on others for energy (e.g., animals).

Classification of Natural Food for Fish

1. Main or Basic Food: Eaten under favorable conditions.
2. Occasional or Secondary Food: Eaten in small quantities when available.
3. Incidental Food: Rarely enters the gut with other items.
4. Emergency or Obligatory Food: Consumed in the absence of basic food for survival.

Classification of Fish Based on Food Variety

• Monophagic: Consumes only one kind of food.
• Stenophagic: Feeds on a limited variety of food.
• Euryphagic: Feeds on a mixed diet without preference.

Classification of Animals by Feeding Method

• Holozoic: Ingests complex food materials directly (e.g., teleosts, elasmobranchs).
• Saprozoic: Absorbs nutrients from dead and decaying matter (e.g., bacteria, fungi).
• Parazoic: Sucks nutrients from live hosts without killing them (e.g., lamprey, hagfish).
  

Classification of Fish Based on Feeding Habits

• Herbivore: Feeds only on plants (75% or more plant material).
• Example: Tilapia, rohu, grass carp.
• Carnivore: Feeds on animals or prey (short, straight intestine).
• Example: Tuna, freshwater shark, giant river catfish.
• Omnivore: Feeds on both plants and animals (intermediate gut length).
• Example: Common carp, mrigal, mahseer.
• Planktivore: Feeds on plankton by filtering water.
• Example: Catla (zooplankton), silver carp (phytoplankton).
• Suspensivore: Feeds on particulate materials in water.
• Detritivore (Scavenger): Feeds on dead and decaying matter.
• Example: Grey mullet, calbasu.
• Corallivore: Feeds on corals.
• Example: Butterflyfish.
• Piscivore: Feeds on other fish.

Types of Carnivorous Fish

1. Insectivorous: Mainly feeds on insects (e.g., trout).
2. Carcinivorous: Mainly feeds on crustaceans (e.g., black bass).
3. Malacovorous: Mainly feeds on molluscs (e.g., black carp).
4. Piscivorous: Feeds on fish of other species (e.g., barracuda).
5. Larvivorous: Feeds on larvae (e.g., mosquito fish).
6. Cannibalistic: Feeds on young of the same species (e.g., murrels, Asian sea bass).

Classification Based on Trophic Niche

• Surface Feeders: Feed on food in the upper water layer (e.g., catla, silver carp).
• Midwater or Column Feeders: Feed in the middle layer (e.g., rohu).
• Bottom Feeders: Feed on benthic fauna (e.g., mrigal, common carp).

Fish Food Groups Based on Ecological Association

• Phytoplankton
• Zooplankton
• Suspended detritus
• Pelagic animals
• Demersal animals
• Settled detritus
• Benthic animals and plants

Types of Feeding

• Predators: Hunt macroscopic organisms (e.g., sharks).
• Grazers: Bite or nibble food (e.g., plankton-feeding fishes).
• Filter Feeders: Use gill rakers to filter food (e.g., phytoplankton feeders).
• Suckers: Extract food from the bottom (e.g., bottom feeders).
• Parasites: Suck body fluids from hosts (e.g., lampreys).

Feeding Stimuli

• Internal Stimuli: Motivation to feed based on season, time, light, hunger, etc.
• External Stimuli: Influences from smell, taste, sight, and lateral-line system.

The interaction of both internal and external stimuli determines feeding behavior in fish.

Fish Feeding Adaptations

Overview

Fish have developed unique feeding adaptations that help them survive in their environments. These adaptations are influenced by both external and internal stimuli.

Key Adaptations

Lips

• Function: The shape and structure of fish lips can vary significantly.
• Adaptation: Some fish have fleshy lips for grasping prey, while others have thinner lips for suction feeding.

Shape of the Mouth

• Function: The mouth shape determines how fish capture and consume food.
• Adaptation:
• Wide mouths: Suitable for gulping large prey.
• Narrow mouths: Ideal for picking small organisms from surfaces.

Teeth

• Function: Teeth help in grasping, tearing, or grinding food.
• Adaptation:
• Sharp teeth: Common in carnivorous fish for catching and holding onto slippery prey.
• Flat teeth: Found in herbivorous fish for grinding plant material.

Gill-rakers

• Function: Gill-rakers are comb-like structures in the gills.
• Adaptation:
• Long and fine gill-rakers: Help filter small particles from the water, useful for plankton-feeding fish.
• Short and stout gill-rakers: Better for catching larger prey.

Digestive Tube

• Function: The length and structure of the digestive tube affect how efficiently fish can process food.
• Adaptation:
• Shorter digestive tubes: Common in carnivorous fish, as they digest meat quickly.
• Longer digestive tubes: Found in herbivorous fish, allowing for the breakdown of tough plant materials.

Conclusion

Fish feeding adaptations are crucial for their survival and vary widely based on their diet and environment. Understanding these adaptations helps in studying fish behavior and ecology.