Characteristics - Ariidae Medium to large sized fish. Two pairs of nostrils closely on each side. Paired maxillary and mental barbels present totally 4-6. Dorsal fin short, with long more or less serrated spine preceded by a very short one. Caudal fin deeply forked. Adipose fin present. Pectoral fin low set, with serrated spine. Colour – Usually greyish blue, dark grey, yellow or brown sometimes with black patches or in some with silvery lateral stripe; pale to white below.

1. Biology of Marine
Catfish
Vinod Kumar
FRM

2. Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Actinopteri
Subclass: Teleostei
Order: Siluriformes
Family: Ariidae, Plotosidae
Subfamily: Ariinae, Bagreinae, Galeichthyinae

3. Characteristics - Ariidae
• Medium to large sized fish.
• Two pairs of nostrils closely on each side.
• Paired maxillary and mental barbels present totally 4-6.
• Dorsal fin short, with long more or less serrated spine preceded by a very short
one.
• Caudal fin deeply forked.
• Adipose fin present.
• Pectoral fin low set, with serrated spine.
• Colour – Usually greyish blue, dark grey, yellow or brown sometimes with black
patches or in some with silvery lateral stripe; pale to white below.

4. Plotosidae
• Also called as eel catfish, coral catfish.
• This family include 41 species in 10 genera.
• Small to moderately large sized catfish.
• 4 pairs of barbels present.
• A pair of nostrils widely separated.
• Two dorsal fin with 1st having serrated spine.
• Adipose fin absent.
• Dendritic organ present.

5. Ariidae Plotosidae

6. Arius arius Arius jella Arius maculatus
Threadfin sea catfish Blackfin sea catfish Spotted catfish
Arius subrostratus Arius sumantranus Arius venosus
Shovelnose catfish Goat catfish Veined catfish

9. Distribution
• Ariids are found worldwide in tropical to warm temperate zones.
• They are found in shallow temperate and tropical sea around the coastlines of
North and South America, Africa, Asia and Australia.
• Plotosids are found in the Western Pacific and the Indian Ocean from east coast
of Africa to Australia.
• Eel catfish are mostly confined to continental margins and islands. Some
members are found on coral reefs & often form dense aggregation.

10. Food & Feeding
• Most of them are omnivorous and scavengers.
• They feed on benthic crustaceans, polychaetes, mollusc, fishes,etc
• Youngones tend to eat small crustaceans, mollusc while juveniles that are still
under protection of male mouthbrooder feeds on planktonic crustaceans.
• The taste buds are abundant near the mouth and on its barbels so having more
taste receptors increases the animal’s ability to detect even trace amounts of
food.

11. • Japanese Sea catfish hunt by detecting changes in water’s acidity level.
• These fish were responding to respiration of small sea worms, polychaetes
which are favourite food of catfish.
• When these tiny worms respire they release carbon dioxide and acid. This acid
changes the pH of the water. The sensory nerves of catfish detect these slight
variations to catch their prey.
• A drop in pH level in ocean could impair their hunting abilities.

12. Dendritic organ
• The dendritic organ is a small fleshy external organ situated on the ventral
caudal surface of Plotosidae catfishes in both sexes from early life stages.
• It is an extra-branchial salt secreting organ for osmoregulation.
• It may be of limited use under extreme salinity conditions.

13. Epidermal Secretion
• The Ariid catfish secrete a thick layer of proteinaceous material when threatened or
injured.
• The chemical and pharmacological properties of this material indicate that it may
promote the healing of wounds.
• The secretion of mucous like gel in response to in a perceived hazard is an externally
expressed defense response and secretion may have a primary function in healing
injury beyond the commonly postulated roles of deterring predators or facilitating
escape.

14. Venomous Gland
• Catfish have serrated bony stings on dorsal and pectoral fins which was used for
defence against predators.
• The cartilaginous, serrated spines are held erect when the catfish is disturbed. In some catfish
species, a integumentary sheath covers a spine.
• Penetration of the skin by spine tears the integumentary sheath exposes the venom gland and
releases the venom into wound. Many of the spine contain sharp serrated teeth that inhibit the
removal of spine from surrounding area.
• The severity of the envenomation ranges from mild following exposure to the fork – tailed catfish
(Ariidae) to potentially serious envenomation by some marine catfish such as oriental or striped
catfish (Plotosus lineatus, Plotosus limbatus and Plotosus canius).
• Primary symptoms are severe pain and swelling at the site of envenomation.

15. Sexual Dimorphism
• At maturity, females develop flap like fatty tissue by their pelvic fins, which
results in them having larger pelvic fins than male.
• This modification is the site of fertilization and play a part in moving the fertilized
eggs to male mouthbrooder for incubation.

16. Reproduction
• Both males and females reach sexual maturity before age 2.
• Arid catfish exhibit paternal mouthbrooders.
• Oral incubations continue through the yolk sac larval state for a total length of 8-
11 weeks.
• The offspring are roughly 6-8cm long and slowly adapt to adult behaviour.
• Mouthbrooding by males counters the relatively low fecundity of females which
only have 20-65 eggs per spawning.

17. IUCN Red List
• Endangered -1
• Vulnerable - 3
• Near Threatened - 1
• Least Concern - 43
• Data deficient - 18
Reason for Threatened
• Biological Resource use
• Residential & commercial development
• Natural system modification
• Pollution

18. Thank You