Perrunichthys perruno ?

[roybryan]

I THINK I HAVE ONE HE IS ABOUT 18 INCHES LONG. CAN SOMEONE DIRECT ME TO ADDING PICS AND SHOW ME THE DIF. OF THEM AND L. LONGBARUS

 

[fishdance]

The number of fin rays (spines) in the dorsal is the easiest way and most reliable way. Leiarius mamoratus aka longibarbis is the most common and almost certainly what you have. P. perruno has 8 (1 hard and 7 soft) dorsal fin rays, Leiarius has 10 or 11. Have a look on planetcatfish or scotcat although they are too similar to distinguish from photos.