Ingredient file // Animal protein
Flounder
Lean fish protein with a watery label weight
Flounder is a lean flatfish added to kibble as fresh or frozen fish material. It supplies protein, but much of its weight is water that leaves during cooking. Its modest oil content does not make the finished food a skin treatment.
- What it is
- Fresh or frozen flounder fish material, prepared for mixing into dog food.
- Made from
- Whole flounder, fillets or ground fish material
- Main job
- Lean animal protein
- Typical amount
- Not published
- Watch for
- Fish allergy and other proteins on the label
- Not the same as
- Fish meal
Straight answer
Is Flounder safe for dogs?
Read the other proteins and the analysis
Flounder high on a bag's list signals fish was added, but its water boosts that position before cooking. Look at the meals and other proteins nearby, then check the finished food's protein, fat and calories. Treat skin, allergy and weight claims as claims about the complete food.
- Why it is in the food
- Lean animal protein
- How common
- Listed by 8 of the 3,205 foods we track
Our read // In our catalog
In 1 of every 401 foods we track
Share of foods that list it
<1%
8 of the 3,205 foods with an ingredient list on file, from 2 brands. 7 dry dog food, 1 freeze-dried dog food.
Each square is 1% of the catalog
Where it sits on the label
Median position 7. In the top five of 3 foods, so it is usually a supporting ingredient.
Above the salt
Almost always listed before the salt, so there is more of it than a pinch.
Price per lb
Median of the cheapest bag price across 7 priced foods, 66% above the catalog. The price is the food's, not the ingredient's.
Who leans on it
50%
of the foods that list it are from Orijen. 2 brands use it in total.
What it is
How it is made
Flounder enters the seafood trade as whole fish or fillets. Pet food suppliers can also prepare seafood material outside the human market, grinding and chilling it so kibble plants can use it.8,9,10
- 01 // Source Caught flounder Commercial fisheries supply flounder that can enter the seafood market whole or as fillets.
- 02 // Process Prepared and ground Pet food suppliers offer flounder whole, as fillets, ground or mechanically separated.
- 03 // Process Kept cold Fish material is supplied as fresh slurry or frozen blocks and usually travels to pet food plants refrigerated.
- 04 // Output Flounder material The chilled or frozen fish reaches the plant for mixing with other ingredients before kibble is cooked.
What is in it
Composition, dry matter
94
% protein
About 94% of the dry matter in sampled European flounder fillets was measured as protein. Fresh fillets were mostly water.
Why it is in the bag
What the manufacturer gets
-
01
Adds animal protein
Flounder flesh contributes protein with little fat. Fresh fish also brings substantial water, so its weight before cooking overstates its share of the finished kibble's solids.5,6
-
02
Adds fish flavor
Fish gives manufacturers another flavor source. Dogs preferred a salmon hydrolysate diet over a chicken control in one test, but that result does not show a preference for flounder.1
-
03
Uses seafood supply
Suppliers offer flounder in several forms, including material outside the human seafood market. That broadens supply; a dog study notes that intact muscle is uncommon in pet food because of expense.4,10
-
04
Offers a lean fish option
A sampled flounder fillet contained little lipid. Manufacturers can use that fish material when formulating fat levels, although added fats and other ingredients determine the finished food's analysis.5,6
How much A flounder-specific feeding amount was not published in these sources; a dog palatability study tested other fish materials at 10% of the diet.1
Our read // The claims
What the evidence supports
Strong: controlled studies in dogs agree. Some: small or mixed dog data. Thin: mechanism or lab work only. None: nothing, or the evidence points the other way.
-
Brands say
Flounder adds protein without much fat
Evidence
- Strong
- Some
- Thin
- None
In a study of 7 European flounder, raw fillets averaged 16.9% protein and 0.94% lipid. That supports the lean-protein description for fillets; whole-fish material need not match those figures.5,10
-
Brands say
Flounder is a low mercury fish
Evidence
- Strong
- Some
- Thin
- None
FDA's 2021 fish-choice chart places flounder among its lower-mercury choices for people. That is a useful species comparison, not a measurement of the fish in a particular bag or a dog feeding trial.7
-
Brands say
Flounder omega 3s soothe itchy skin
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
In a crossover trial of 16 dogs, marine oil capsules significantly improved pruritus, alopecia and coat character compared with corn oil capsules over time (P<0.02 to P<0.001). The trial tested concentrated oil capsules, not flounder, and a flounder listing gives no EPA or DHA dose to compare with it.2
-
Owners say
Flounder helps dogs lose weight
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
Lean fish does not determine a finished food's calories. In a trial with 10 hounds, protein portions from pollock, salmon and other meats changed some satiety markers but did not reduce voluntary food intake.4,5
-
Owners say
Flounder is safe for fish allergic dogs
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
Cod exposure triggered symptoms in 27 dogs identified as cod allergic, and lab tests found antibody recognition of proteins from several fish species. Flounder was not challenged, so its different name offers no assurance.3
Straight answers
What owners ask
-
Q01
Is it just filler?
NoFlounder supplies animal protein. Its raw weight includes water, so a high place on the ingredient list does not tell you how much fish protein remains in the finished kibble.5,6
-
Q02
Does first mean most protein?
Not necessarilyIngredients are listed by weight, and fresh flounder brings water into that weighing. Dry meals bring concentrated solids. Read the other protein ingredients and the finished food's analysis before judging how much fish protein it contains.5,6
-
Q03
Is this a weight control food?
No proofFlounder is lean, but the complete recipe sets the calorie level. A dog study comparing fish and meat protein portions found changes in some appetite markers without a drop in how much dogs ate.4,5
Who uses it
Brands, best sellers and the company it keeps
Top brands, by foods that list it
Foods that list it / all the brand's recipes we track.
Usually listed with, share of the foods that list it
- Whole Herring 63%
- Red Lentils 50%
- Herring Meal 38%
- Pollock Meal 38%
- Chicken 38%
- Turkey 38%
- Salmon 25%
- Sunflower Oil 25%
- Whole Mackerel 25%
- Chicken Meal 25%
- Turkey Meal 25%
- Green Peas 25%
On the shelf
Foods that list Flounder
8 foods in our catalog list it, highest on the label first.
On labels as
Other names for this
Manufacturers do not all use the same wording. These all mean the same thing.
Sources
What we read
Checked October 1, 2026.
- 1 Fish meals, fish components, and fish protein hydrolysates as potential ingredients in pet foods
- 2 Double-blinded Crossover Study with Marine Oil Supplementation Containing High-dose icosapentaenoic Acid for the Treatment of Canine Pruritic Skin Disease
- 3 IgE reactivity to fish allergens from Pacific cod (Gadus macrocephalus) in atopic dogs
- 4 Acute satiety response of mammalian, avian and fish proteins in dogs
- 5 Nutritional profiling and contaminant levels of five underutilized fish species in Norway
- 6 Reading Labels
- 7 Advice about Eating Fish
- 8 Summer Flounder: Commercial
- 9 How Pet Food Is Made
- 10 Pet Protein
- 11 Selecting and Serving Fresh and Frozen Seafood Safely