By Koaw - March, 2021

The following text is based upon the script for the video I made for this hybrid walkthrough. Reading or watching the video will do ya fine!

WALK-THROUGH #2 Introduction: Identifying hybrid lepomids, or common sunfishes, is no simple task—especially considering that theoretically all of the 13 recognized species of lepomids can hybridize with each other, creating a possible 78 combinations. And of those 13 species, individual species can vary greatly in appearance, especially across regional populations, making hybrid ID’s even trickier. More often than not you can’t be 100% confident on a hybrid ID without a DNA analysis. However, if you know your lepomid is just not looking like a pure specimen, I’ll show you how to narrow down your possibilities and come to the best educated guess possible.

STEP 1: LEARN THE ANATOMICAL DIRECTIONALITIES & BASIC SUNFISH FEATURES

I believe all fishers should at least know the basic 4 anatomical directionalities and some basic features (body parts) on fishes. Check out STEP 1 to advance your skills. (STEP 1 LINKED HERE.)

STEP 2: LEARN THE BASIC FEATURES OF THE SPECIES

Before identifying hybrids it is essential to understand how to differentiate the species within the genus. Even learning 2 or 3 traits of of each species will help you out. Check out the individual species pages or STEP 2 to learn more. (STEP 2 LINKED HERE.)

STEP 3: GET PHOTOGRAPHS OF THE FISH

In STEP 3 of the sunfish guide I cover what photographs to capture in order to confirm your fish. Always start with a good lateral shot that captures most of the fish and gets the fins splayed as much as possible. Also grab a close-up shot of the head, the pectoral fin and the gill rakers. Any other shots will be helpful. Definitely grab a shot of the gill rakers as this may be a make-it or break-it for an ID on hybrids. See the below video on how to look at gill rakers.

CLICKING ON THE BELOW IMAGES WILL ENLARGE THEM.

The adjacent video shows you how to look at gill rakers on sunfishes.

It’s apparent from the lateral pattern, colors and opercular flap that this fish is likely a hybrid. We’ll cover what to look for in STEP 5.

STEP 4: LIST ALL NEARBY LEPOMIDS

This is a very important step for identifying hybrids. I caught this fish in N. Virginia on a small lake. It’s time to use the resources in STEP 4 and make a list of all possible species in this lake as well as in nearby waters.

The confirmed species in the lake are green sunfish (Lepomis cyanellus), bluegill (Lepomis macrochirus), redear sunfish (Lepomis microlophus), and warmouth (Lepomis gulosus). Other species caught nearby (within a 25 mile/40 km) radius are the redbreast sunfish (Lepomis auritus), pumpkinseed (Lepomis gibbosus) and longear sunfish (Lepomis megalotis).

That’s seven different species nearby!

SHORT LIST: GREEN, BLUEGILL, REDEAR, WARMOUTH, REDBREAST, PUMPKINSEED & LONGEAR.

STEP 5: ANALYZE THE FISH

Hybrids will often display intermediary characteristics between the parent species but that is not always the case. Sometimes a feature or multiple features of one parent species are strongly expressed and not the other parent’s features. Let’s break down some important characteristics on this specimen.

MOUTH/JAW SIZE:

The mouth/jaw on the hybrid specimen in question is large. The maxilla’s posterior end aligns well past the anterior portion of the pupil.

Only two species of lepomids will show mouths this large: The warmouth and green sunfish. Occasionally the redbreast will have a mouth this large.

The three species with the smallest mouths/jaws are the bluegill, pumpkinseed and redear sunfish, all three are on the list of possible parent species. Based on the mouth size, it is highly unlikely that either of these species would be a parent species. We would expect the mouth to be smaller on this hybrid if a bluegill, pumpkinseed or redear sunfish was a parent species. But this isn’t enough to eliminate any species from contention.

PECTORAL FIN SIZE AND SHAPE:

The shape of this hybrid’s pectoral fin is roundly and it is very short; if bent forward this pectoral fin wouldn’t even extend to the posterior end of the eye.

Again, like we saw with the mouth/jaw size, only two species of lepomids often show a pectoral fin this short and roundly: the warmouth and green sunfish.

And once again, like we saw with the mouth/jaw size, the three species with the longest pectoral fins that are also pointy are the pumpkinseed, bluegill and redear sunfish. The pectoral fins on these species most often extend past the eye if bent forward. We would really expect the pectoral fin to be longer if either of these three species were a parent species.

Considering this hybrid’s mouth/jaw is so large and the pectoral fin is so short and roundly, as well as the fact I’m not seeing any features of pumpkinseed, redear sunfish or bluegill in this hybrid, I’m going to eliminate these three species.

ELIMINATED: BLUEGILL, REDEAR, & PUMPKINSEED
REMAINING: GREEN, WARMOUTH, LONGEAR, & REDBREAST.

GILL RAKERS: Now let’s look at the gill rakers. The rakers on this fish are long and thin. The warmouth typically has very long and thin rakers and the green sunfish has long and thin rakers. Redbreast rakers have been shown to be quite variable in length, but they are usually thick. And longear rakers and short and thick. The rakers on our specimen are long and thin don’t look anything like redbreast or longear gill rakers.

Though intermediate characteristics are typical of hybrids, it doesn’t always occur, so I don’t think we can eliminate the redbreast and longear from the analysis quite yet. But we would expect the rakers of our specimen to be somewhat shorter and thicker if a longear was involved—and most likely thicker if a redbreast was involved. So the picture is getting clearer. (For your reference, I did place all the commonly seen raker sizes for all the species in STEP 5 “Koaw’s Cheat Sheet.”)

OPERCULAR FLAP:

Now let’s look at the opercular flap—usually a good clue for hybrid and pure specimen IDs. This specimen has an earflap with diluted red and purple, with anterior and posterior pale edging. The warmouth and green sunfish typically have that diluted red and purple color on the back of the ear flap. Longear may also show some color in that area. However redbreast do not have any color on the posterior edge of the ear flap.

Also, let’s look at the length of this ear flap. It’s not too large—and definitely a bit oddly pointed. Redbreast and longear have the two longest ear flaps of all the lepomids—and these flaps are typically longer on males. Although this specimen looks full of eggs, if we look at the tiny urogenital opening of our specimen which is just posterior to the anus, we can be pretty sure this is a male. If it were a female plump with eggs that urogenital opening would be larger and swollen. This is just a well-fed male.

So if there were longear or redbreast in this fish—we would really expect a slightly longer earflap. I’m almost confident enough to eliminate the longear and redbreast, based off the rakers and the ear flap. But let’s also look at the upper lip.

UPPER LIP: Typically longear and redbreast will have a blue streak across the entire upper lip. On green sunfish, this blue on the lip is short, normally limited to the lateral sides. And warmouth do not have a blue streak. Our specimen shows only a faint bit of blue streaking, like a green sunfish’s but diluted.

With that and our previous criteria, as well as the fact I’m not seeing any other traits of longear and redbreast on this specimen—I’m going to eliminate these two species.

ELIMINATED: BLUEGILL, REDEAR, PUMPKINSEED, LONGEAR, & REDBREAST.
PARENT SPECIES: GREEN & WARMOUTH.

So we believe our parent species are the green sunfish and warmouth. Let’s examine more reasons to support our conclusion.

FIN RAY/SPINE COUNTS: The basic meristics on this fish is as follows: 3 anal spines, 9 anal rays, 10 dorsal spines, 9 dorsal rays, & 13 pectoral rays (L). These counts fall within the ranges of the green sunfish and warmouth, especially with the 9 anal rays and 9 dorsal rays—where those counts are usually 1 or 2 higher on the other lepomids around here.

COLOR/PATTERNING:

The white and orange along the median fins is a common green sunfish feature and usually persists through on hybrids with a green parent. The dark spots/mottling in the median fins is a trait of the warmouth. Warmouth usually have dark lines radiating from the eyes and we can see the dark lines from our specimen are there—but kind of mashed together. And these dark mashed lines with the blue streaking along the head very much so look like intermediacy of pattern between the warmouth and green. The lateral pattern along the body also appears like good intermediacy with the pale blue spotting and lattice network on that dark brown top.

TOOTH PATCH ON TONGUE:

This specimen did not have a tooth patch on the tongue. Typically only warmouth have a well-developed tooth patch on the tongue. But it is more common that a hybrid with a warmouth parent will not show a well-developed tooth patch on the tongue; I’m not concerned about that absence of glossohyal teeth suggesting a warmouth isn’t involved.

With our empirical evidence stacked up, all signs are pointing to a warmouth (L. gulosus) x green sunfish (L. cyanellus) mix. I’ve casually given this hybrid combination the common name ‘wargreen’; it just seemed better than greenwar! The specimen is most likely an F1 hybrid but there is no way to know if this is second generation or perhaps a backcrossed specimen or even if an introgression happened earlier in the ancestry.

Hybrid IDs are fun challenges. I really hope I was able to help you out for when you encounter hybrids! Don’t forget to subscribe to KNFS on the YouTube Channel!

Cheers! -Koaw

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