Question

Which among the following has shorter value of relative gut length than others?

• A. Hypophthalmichthys molitrix
• B. Channa striata
• C. Chanos chanos
• D. Labeo rohita

Hint:

RGL Relationship:
Carnivore $<$ Omnivore $<$ Herbivore.
Think of Channa (Snakehead) as a predator; it needs a quick, efficient gut for high-protein meat.
Herbivores like Silver Carp need massive "plumbing" to extract nutrients from algae.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to identify the fish with the shortest Relative Gut Length (RGL). RGL is the ratio of the length of the digestive tract to the total body length of the fish.
Key Formula or Approach:
The RGL value is directly related to the feeding habits of the fish:
1. Carnivores: Have short guts (RGL $<$ 1) because meat is easy to digest and high in energy.
2. Omnivores: Have intermediate gut lengths (RGL approx. 1 to 3).
3. Herbivores/Detritivores: Have very long, coiled guts (RGL $>$ 3) to provide more surface area and time for the digestion of complex plant materials like cellulose.

Step 2: Detailed Explanation:

• Analysis of Options:
• Hypophthalmichthys molitrix (Silver carp): It is a phytoplankton feeder (herbivore). It has an extremely long gut.

• Channa striata (Striped snakehead): It is a strict carnivore (piscivorous). Its gut is short and relatively straight. RGL is typically less than 1.

• Chanos chanos (Milkfish): It is an omnivore/micro-herbivore. It has a fairly long gut for processing algae and detritus.

• Labeo rohita (Rohu): It is an omnivore tending towards herbivory (column feeder). It has a long, coiled gut.

• Conclusion: Since Channa striata is the only carnivore in the list, it will have the shortest relative gut length.

Step 3: Final Answer:
Channa striata has the shortest RGL.