Which of the following are the fishery by-products?
(i) Oil , (ii) Manure
(iii) Glue , (iv) Isinglass
(v) Shagreen , (vi) Leather

Options

A. (i), (ii) and (vi)
B. (iii), (iv) and (v)
C. (i), (iii) and (vi)
D. All of these

Explanation

To determine which of the following are fishery by-products, we will analyze each option provided:

1. **Oil**: Fish oil is derived from the body and liver of fish. It is commonly used for medicinal purposes. Therefore, oil is a fishery by-product.

2. **Manure**: The remains and feces of fish can be used as manure. This is a common practice in agriculture to enhance soil fertility. Thus, manure is also a fishery by-product.

3. **Glue**: Glue can be obtained by heating the skin and bones of fish in water. This process extracts collagen, which is used to make glue. Therefore, glue is a fishery by-product.

4. **Isinglass**: Isinglass is derived from the dried swim bladder of fish. It is used as a gelatinous substance in various applications, including clarifying beverages. Hence, isinglass is a fishery by-product.

5. **Shagreen**: Shagreen is a decorative material made from the skin of sharks. It is used in various crafts and products. Thus, shagreen is a fishery by-product.

6. **Leather**: Fish skin can be processed to produce leather, similar to how leather is made from cowhide. Therefore, leather is also a fishery by-product.

In conclusion, all the options listed (i.e., oil, manure, glue, isinglass, shagreen, and leather) are fishery by-products.

### Final Answer:
All of the following are fishery by-products:
(i) Oil, (ii) Manure, (iii) Glue, (iv) Isinglass, (v) Shagreen, (vi) Leather.