The document discusses the structure of fish skin, noting that it consists of an epidermis layer containing glands like mucous and poison glands, and a dermis layer where scales come in four types - placoid, cycloid, rhombic, and ctenoid. The dermis contains pigment cells like melanophores, xanthophores, and iridophores that contain pigments like melanin, carotenoids, and guanine crystals which give fishes their color and ability to reflect light. References on fish skin structure include modern textbooks by Kotpal and books on zoology by S.M. Sexsena and

1. Shri Shankaracharya Mahavidyalaya, Junwani , Bhilai
Fish skin
Dr. Sonia Bajaj
(Head of Department)

2. Structure of Skin of Fishes
•The Epidermis layer of skin in fishes:
•Epidermal glands:--The epithelium of
epidermis is modified into a variety of
glands, which are:
•(i) Mucous gland:
•(ii) Poison glands:
•(iii) Photophores:
•The Dermis layer of skin in fishes:-On
the basis of shape, scales are of four
types:
•(i) Plate like or placoid scales commonly
found in Elasmobranches.
•(ii) Cycloid scales found in Burbot and
soft-rayed fishes.
•(iii) Rhombic or diamond shaped scales,
common among gars and sturgeons.
• (iv) Ctenoid scales, characteristics of
spiny-rayed bony fishes
(Acanthopterygii).

4. Dermis
• Underneath the epidermis Inner stratum spongiosm
Outer stratum compactum Collagen fibres .
• Fishes such as glass catfish, glass eel, the arrangement
of collagen fibres is extremely regular.
• Allowing light to pass through the dermis unreflect.
• In these fish the peritoneum is pigmented to protect
the abdominal organs from light Pigment cells.
• Dermis contains pigment cells that can occur in layers
at different levels.
• Pigment cells contain vareity of pigments other than
melanin Carotenoids Pterin Guanine crystals(silvery color)
Melanophores.
• Containing melanin absorbs the entire visible range of
light Astronotus ocellatus Melanophores (dark-brown)
are located in the dermis.
Xanthophores • Contains rhodopterin and carotenoid
granules and appear yellow to orange.
Iridophores • Cells that contain platelets of guanine or
hypoxanthine are called iridophores.
• These cells reflect light rather than absorb it giving fish
their shiney appearance.

5. References-
Modern text book -Kotpal
Jantu Vigyan- S.M. sexsena
Jantu Vigyan- Dr.H.N. Baijal