Taxonomy of Finfish (1+2)

Procedure

·        Based on the following character identify the order Siluriformes.

·        .

·         Mesopterygoid very reduced

·         Pre opercle and inter opercle relatively small

·         Adipose fin usually present

·         Spine like (= spinous) rays present at the front of the dorsal and pectoral fins

·         Dorsal fin of most cat fishes has two spines; the first being very short and forming a locking mechanism for the second spine.

·         Body either naked or covered with bony plates.

·         Usually up to four pairs of barbels on head (one on nasal, one on maxillary and two on chin)

·         The nasal and chin barbells may be variously absent.

·         Maxilla  toothless and rudimentary

·         Caudal fin rays 18 or fewer (most with 17)

·         Caudal skeleton varying between having six separate hypural plates to complete fusion of caudal elements.

·         Eye usually small

 

 

Group the fishes based on the following character.

 

 

Bagridae (bagrid cat fishes)

o   Freshwater, Africa and Asia (to Japan & Borneo)

o   Dorsal fin has one spine along with 6 or 7 soft rays (rarely 8 – 20)

o   Adipose fin present and highly variable in size between species

o   Pectoral fin serrated

o   Usually four pairs of well developed barbells

o   Mystus

o   Rita    

 

Siluridae (sheat fishes)

 

·                 Freshwater, Europe and Asia

·                 Dorsal fin usually with fewer than seven rays, sometimes absent, not preceded by a spine.

·                 Anal fin base very elongate (41 – 110 rays)

·                 Nasal barbell absent

·                 1 or 2 pairs of barbells on lower jaw, and maxillary barbels usually elongate.

·                 Largest species of this family is Silurus glanis which commonly reaches 3m.

 

·         Wallago

 

Pangasiidae

 

·         Freshwater, southern Asia (Pakistan to Borneo).

·         Usually two pairs of barbells (maxillary and one pair of mandibular or mental barbells present, nasal barbells always absent, only maxillary barbels in adult Pangasius gigas.

·         Body compressed

·         Adipose fin present, small, and never confluent with caudal fin.

·         Dorsal fin far forward with one or two spines of 5-7 soft rays.

·         Anal fin  with 26 -46 rays

·         Vertebrate – 39 -52

·         Pangasius

Clarridae – (Air breathing catfishes)

o   Freshwater

o   Distributed through Africa, Syria, southern and western Asia

o   Dorsal fin base very long, with more than 30 rays not preceded by  a spine, separate or continuous with caudal fin.

o   Pectoral and pelvic fins absent in some species

o   Caudal fin rounded gill openings wide

o   Four pairs of barbells

o   Air breathing labyrinthic organ arising from gill arches

·         Clarias

 

 

Based on the figures given identify some of the similar species available in your region.

Finally write the classification.