How to Identify Tadpole Madtom

To identify Tadpole Madtom (Noturus gyrinus), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Dorsally, the body is typically dark brown to olive-brown, often mottled with darker blotches. The sides are lighter, transitioning to a pale yellow or whitish belly. The fins are generally dusky, sometimes with a pale margin. There is often a faint, dark lateral stripe.

Scale type

none

Mouth position

terminal

Distinctive features

Stout, tadpole-like body, particularly in juveniles., Adipose fin broadly joined to the caudal fin, forming a continuous fin margin., Small, beady eyes., Four pairs of barbels around the mouth., Venomous pectoral and dorsal fin spines.

Dorsal fin

Single dorsal fin with a strong, serrated spine and 6-7 soft rays. The spine is venomous.

Tail fin

Caudal fin is rounded to slightly emarginate and broadly confluent with the adipose fin, giving it a continuous appearance.

Pectoral fin

Pectoral fins have a strong, serrated spine (venomous) and 7-9 soft rays.

Distinctive fins

Adipose fin is long and low, broadly connected to the caudal fin, a key characteristic distinguishing it from other madtom species where the adipose fin is often free or only narrowly joined.

Identification Tips

1. 1

   Body Shape

   Look for a relatively stout, somewhat compressed body that tapers towards the tail, resembling a tadpole, especially in younger individuals.

2. 2

   Adipose Fin

   The most reliable distinguishing feature is the adipose fin being broadly connected to the caudal (tail) fin, forming a continuous fin margin. This is a key characteristic for separating it from most other Noturus species.

3. 3

   Coloration

   Observe the dark brown to olive-brown dorsal coloration with lighter sides and a pale belly. Mottling or a faint lateral stripe may be present.

4. 4

   Fin Spines

   Note the presence of strong, serrated spines in the dorsal and pectoral fins. Exercise caution as these are venomous.

5. 5

   Size

   Adults typically range from 7-13 cm (2.8-5.1 inches) in total length, rarely exceeding 15 cm (6 inches).

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