Description

The dusky redhorse is very difficult to distinguish from the Golden Redhorse. Therefore, some identification tips are in order! (Thanks to Joshua Knuth for all of the illustrations)

Identification

When you're thinking that a fish might be a dusky redhorse, first look at the tail. It should not be bright red. Then, make sure it doesn't have an arched back and a large, fan-shaped dorsal - in which case it would be a silver. Having narrowed it down to golden or dusky (depending on your region), you then need to dig a little deeper.

Tubercules

Tubercules are hard, toothlike bumps that redhorse develop on their bodies. Male Golden Redhorse develop very large, pointed tubercules on their head during the springtime while spawning. Black Redhorse do not develop these structures - they may get some tiny, pepper-grain-sized tubercules or none at all. Therefore, if you see a bunch of large white bumps on the nose of the fish, then it's not a black redhorse. Check out the Golden redhorse Page to see some good shots of tuberculate male goldens.

Scales

OK, if you don't see any large tubercules, then it's time to count some scales. Black redhorse have 44 to 47 pored scales between the cliethrum and the hypeural plate, along the lateral line (versus 39 to 42 for the golden); typically I look for 45 or more scales before going any further.

Remember, you're only counting the large scales that are not deformed and have a lateral line pore. Beware of deformed or regenerated scales - redhorse can often have weird, twisted-looking (helical) scale patterns that can mess up the scale counting. This can make the lateral line count invalid - at least on one side of the fish. You'll end up counting a straight line of scales right down the side of the fish, skipping any compressed or non-pored scales at the head as well as any thin and compressed scales right at the tail.

In addition, the caudal peduncle of the black redhorse is very narrow in comparison to the golden redhorse; this really stands out when you step back and look at the fish as a whole. This diagram shows the correct proportions.

Caudal Peduncle Proportions

A reliable indicator that many use is the length versus depth proportion of the caudal peducle. Measure the length of the caudal peducle - this is the distance from the posterior edge of the base of the anal fin to the posterior edge of the hypural plate. Then measure the depth or height of the caudal peduncle at its center. This is easy to do in photographs as long as the fish is laying flat. These measurements are taken and then divided, length over depth. Black redhorse typically have depth that is 59.9% or less and Golden redhorse have a depth of 62% or more. Once you get used to looking for this, it really starts to jump out at you.

Other Characteristics

Black Redhorse also tend to have a more cylindrical, long-bodied shape, as opposed to the stockier, more arched look of the golden redhorse. Certain specimens of the black redhorse also show a weird, almost translucent green coloration that can be striking - epecially during the breeding season.