To identify fish species, measurements, counts of anatomical features, and color patterns are used. Meristic traits involve counting scales, fins, spines, and soft rays. Morphometric traits involve measuring features like standard length, head length, and fin lengths relative to standard length. To identify an unknown fish, samples are collected and their meristic traits like scale counts and fin formulas are recorded, along with morphometric trait measurements, which are then compared to published identification standards.

1. Identification of Fishes:
To identify species of a fish following tools are used.
 Morphometric
- measurements relative to length
 Meristic
- counts
 Anatomical traits - shape, presence/absence
 Color patterns

2. Meristic: (Counting)
1. Scale counts:
Lateral line scale count
Scales above lateral line
Scales below lateral line
Scales before dorsal fin

4. 2. Fin (Ray and Spines) count:
 Spines: Single‐shafted, entire composition,
designated by roman numerals.
 Soft rays: Bilaterally paired, segmented, branched,
flexible, designated by Arabic numerals.
 Fin formulae: Counting of each fin ( number of Spines and
Rays)
 A fin may contain them both.
 Example: D XIII 12, A III 15, P 6, V I 6, C 9
 (D dorsal, A – anal, P – pectoral, v – ventral or pelvic, C –
caudal).

5. Morphometric: (Measurement)
 Standard length (From snout to base of caudal fin)
 Head length ( Snout to Operculum)
 Snout length (Diatance between eye orbit and mouth tip)
 Dorsal Fin Length
 Pelvic fin length
 Pectoral fin length
 Caudal fin length
 Anal fin length

6. Eye orbit Length
Upper jaw length
Body depth
 Pointed dividers or dial‐reading
calipers are used.
Measurements are recorded in% of
Standard length.

7. Procedure:
 Take sample fish, Take more then one fish
as sample.
 Collect Required Standard data bout fish
in published form.
 Take observation of Morphometric and
meristic.
 Tele your observations with standard
readings.