Isichthys henryi
Isichthys henryi
Isichthys henryi is an African freshwater fish from the family of mormyrids ( Mormyridae ). It comes in two separate areas of distribution before in West Africa. This includes a coastal rivers in Guinea, Sierra Leone and Liberia, the other is located in the basin of the Niger and ranges from Cameroon and Gabon to Kouilou in the Republic of Congo.
Features
Isichthys henryi is a maximum of 28.7 cm long and has an eel-like elongated, slightly laterally flattened body. The hull is solid dyed in the color of dark chocolate, the head is yellow-brown, the fin rays dark brown, the fins transparent membrane. The body height is 5.9 to 11.9 % of standard length, body width 70 % of the body height. Dorsal and anal fins are long, the dorsal fin, which reaches 44 to 48 % of standard length begins well before the anal fin. It is supported in the population of Niger and Lower Guinea 42-49 fin rays, in the population from Upper Guinea, there are 37 to 44 fin rays. The anal fin reaches 39 to 41 % of the standard length and has 40 to 48 or 36 to 44 fin rays. From the equally elongated Brienomyrus species - and some elongated Mormyrops species - can Isichthys henryi are distinguished by the long dorsal fin; at Brienomyrus and Mormyrops is always the anal fin the longest.
The pelvic fins are at Isichthys henryi closer to the anal fin than to the pectoral fins. The tail fins stem is short and reaches only 8% of standard length. It is 1.7 to 3.3 times longer than high and surrounded 16-20 scales, which, however, sometimes be irregular, so that it is difficult to determine the number of scales. Along the sidelines, one counts in the population of Niger and Lower Guinea 120 to 130 scales, in the population from Upper Guinea there are 135 to 145 scales.
The head is 1,75 to 2 times as long as high. The " snout " (Region before the eyes ) accounts for 21-25 % of head length and terminates in a rounded " Knoll organ ". The mouth is inferior and the upper jaw with five to six, occupied in the mandible with six bicuspid teeth. On the lower jaw outside sitting electroreceptors. The eyes are small, their diameter reaches half the snout length. Around the eyes, there are four more large electrical receptors whose diameter corresponds to the nasal openings.
Like all mormyrids is Isichthys henryi for electric communication and electrical orientation capable. Electric receptors are located on the head, back, and at some parts of the belly. You are missing on the sides and on the tail fins stem, where the electric organ can be found. The electrical signal from Isichthys henryi is different from low frequency and in females and males.
System
Isichthys henryi is the only species of the genus Isichthys. Although there are differences between the two populations with respect to the fin rays number and scale rows, they are considered insufficient to split the type into two types. Isichthys is the sister genus of Brienomyrus.