Kosher dietary laws determine what Jewish people who observe kashrut can eat, how food must be prepared, and which foods can share a meal. The rules come from the Torah, primarily Leviticus 11 and Deuteronomy 14, and have been applied and explained by rabbinical authorities for centuries. Once you see the structure, the system is easier to follow than it first appears: food falls into one of three categories, certain things are always forbidden, and certified products carry a symbol called a hechsher to show they have been inspected. If you want to look up whether a specific fish is kosher, you can use the KosherFish lookup tool or browse the full kosher fish list.
The Three Categories of Kosher Dietary Laws: Meat, Dairy, and Pareve
Every food in a kosher kitchen belongs to one of three categories: meat (fleishig in Yiddish), dairy (milchig), or neutral (pareve). Meat and dairy cannot be eaten together, cooked in the same pot, or served on the same plates. Pareve foods are neutral and can go with either a meat meal or a dairy meal.
Meat and poultry (fleishig) includes beef, lamb, veal, chicken, turkey, duck, and their byproducts. Meat and poultry are considered kosher under Jewish law only when the animal is a permitted species, slaughtered by a trained shochet (ritual slaughterer) following the laws of shechitah, and the blood removed through salting or broiling. Permitted animals are even-toed hoofed mammals that chew their cud, per Leviticus 11:2-8. Permitted kosher birds include chicken, turkey, duck, and goose. Birds of prey are not considered kosher.
Dairy (milchig) covers milk, butter, cheese, yogurt, and any food produced with dairy ingredients. According to Jewish law, the dairy must come from a kosher animal. Many communities also require that dairy products be supervised from milking onward (chalav Yisrael), although this is a chumra (a stringency), not a universal requirement.
Pareve means neither meat nor dairy. Fruits, vegetables, grains, eggs, and fish are all pareve. You can eat pareve food with a meat meal or a dairy meal. Fish, specifically, is pareve under kosher law, which is why lox with cream cheese is a perfectly kosher combination. Pareve status can be lost if a food is cooked in a meat or dairy pot that was recently used.
The Meat-Dairy Separation and What It Means in Practice
The Torah states three times that you must not boil a kid in its mother’s milk (Exodus 23:19, 34:26, and Deuteronomy 14:21). From those verses, the rabbis derived a complete prohibition on mixing meat and dairy: not just avoiding a single dish that combines them, but keeping separate sets of dishes, pots, utensils, and counter space. Most kosher kitchens have two full sets of everything.
There are also waiting periods. After eating meat, many Ashkenazi communities wait six hours before eating dairy. Some Sephardic communities wait one hour. Going the other direction (dairy before meat) typically requires only rinsing the mouth and eating something neutral, with variations by community custom and posek (rabbinic decisor).
At first, the rules can look complicated. In practice, though, the system is predictable once you know which foods belong to which category. Most people who observe kashrut find that it becomes routine quickly, especially with clear labeling and certified products widely available in modern grocery stores.
Where Fish Fits: Kosher, Pareve, and the Fins-and-Scales Rule
Fish is pareve, not meat, under kosher law. That is why you can eat salmon at a dairy meal or herring alongside a dairy appetizer without any concern about meat-dairy mixing. But fish has its own kosher requirement: it must have both fins and scales, and the scales must be the type that come off without tearing the skin.
This test comes directly from Leviticus 11:9-12 and Deuteronomy 14:9-10. The Orthodox Union and the Chicago Rabbinical Council (cRc) both apply it to maintain their respective kosher fish lists. The scales must be ctenoid or cycloid scales, the kind you can pinch and remove. Fish with embedded ganoid scales (like sturgeon) or placoid scales that are actually skin denticles (like sharks) do not qualify, even though those animals have something called “scales” in biology.
That is why salmon, tuna, trout, cod, and flounder are kosher, while catfish, shark, sturgeon, and eel are not. Shrimp, lobster, crab, and all other shellfish are also not kosher, because they have no fins or removable scales at all.
There is also a custom in many communities not to eat fish and meat together on the same plate or in the same dish. This is a minhag (custom), not a Torah-level prohibition, and the rules vary. The OU and cRc recognize this custom. You can eat fish at the same meal as meat, just served separately and not mixed. You can read more about this in our guide to eating fish and meat together.
For a full explanation of the fins-and-scales test and how it is applied to specific species, see our guide on what makes a fish kosher.
Foods That Are Never Kosher
Jewish dietary law categorizes certain animals and foods as inherently forbidden, no matter how they are prepared or what certification they carry:
- Pork and its byproducts (including lard and pork-derived gelatin). Pigs have split hooves but do not chew their cud, so they are not considered kosher land animals according to Jewish dietary law (Leviticus 11:7). The rule applies to any pig-derived ingredient.
- Shellfish: shrimp, crab, lobster, clams, oysters, scallops, mussels. No fins, no removable scales.
- Certain fish: catfish, shark, sturgeon, eel, ray, and all other fish without the right kind of removable scales.
- Blood: blood must be removed from meat through salting (melicha) or broiling before it is eaten. Eggs with blood spots are typically removed or discarded.
- Non-kosher birds: birds of prey are not kosher. Chicken, turkey, duck, and goose are all permitted, provided they are properly slaughtered and prepared.
- Insects: even tiny insects are not kosher. Because many insects are invisible to the naked eye in leafy greens like romaine lettuce and herbs, careful checking or pre-washed certified greens are required under kashrut. Fruits and vegetables themselves are permitted, but they must be bug-free.
- Non-kosher slaughter: even a kosher species is not kosher if it was not slaughtered by a shochet following the laws of shechitah.
Kosher Certification: What Hechshers Mean and Which Ones to Trust
A hechsher is a kosher certification mark placed on packaged food to show it has been inspected by a recognized agency. The agency verifies that the product meets kosher dietary laws by checking ingredients, the production facility, and the processes involved.
The most widely recognized agencies in the United States:
- OU (Orthodox Union): a U inside a circle, sometimes with a D for dairy or a P for Passover. The largest kosher certifier in the world. Their kosher fish list and fish-status rulings are a standard reference.
- cRc (Chicago Rabbinical Council): a C inside a diamond. They publish a well-known kosher fish list and detailed consumer guides.
- Star-K: a K inside a six-pointed star.
- OK Kosher: a K inside a circle.
- Kof-K: a K inside a hexagon.
A plain “K” with no enclosing symbol or agency name can mean the manufacturer is self-certifying with no third-party inspection. Many observant Jews do not rely on a plain K. If you are unsure about a product, check whether a recognized agency backs the mark.
For fish specifically, a hechsher matters most on processed products: canned fish, smoked fish, fish sticks, fish fillets in breading, and anything where you cannot see the original whole fish with skin and scales. A whole fresh fish with its skin and scales intact is usually verifiable without a hechsher (you can identify the species yourself). Processed fish is a different story. Our guide on whether fish needs a hechsher covers this in detail. For a full breakdown of kosher symbols, see our kosher symbols explained guide.
Kosher for Passover: An Extra Layer
Passover (Pesach) adds rules on top of the kosher dietary laws that apply year-round. During Passover, leavened grain products (chametz) are completely forbidden in the home and at the table. Bread, pasta, most cereals, beer, and many other processed grain foods are chametz. Any kosher food consumed during Passover needs separate Passover certification to confirm no chametz was involved in production or processing.
Ashkenazi Jews also have a custom of avoiding kitniyot (legumes, rice, corn, and similar items) during Passover, though this is a stringency, not a Torah prohibition, and Sephardic Jews generally do not follow it. Fish remains kosher for Passover without extra restrictions, as long as it meets the standard fins-and-scales requirement and any processed fish carries Passover certification.
Grape Products and Kosher Wine
Grape products hold a special place in Jewish dietary law. According to the Talmud, wine and grape juice that are not produced under Jewish supervision are not considered kosher. This applies to wine, grape juice, grape-derived vinegar, and wine-based sauces. The rule traces back to concerns about wine used in ancient non-Jewish religious rites. Today, mainstream kosher agencies like the OU and Star-K certify kosher wines and grape products, and a hechsher on any grape-based product matters more than for most other foods.
Grape products also connect to Shabbat and the holidays in a direct way. Kiddush (the blessing over wine on Shabbat and Yom Tov) requires a kosher wine or grape juice. Many observant families use specifically Mevushal wine (briefly cooked), which maintains its kosher status even after being poured or handled by a non-Jewish person, making it practical for restaurants and catered events.
| Food | Category | Kosher? | Why |
|---|---|---|---|
| Beef steak (from shochet) | Meat | ✅ Yes | Kosher species, proper slaughter |
| Chicken (from kosher butcher) | Meat | ✅ Yes | Kosher bird, shechitah-slaughtered |
| Milk, cheese | Dairy | ✅ Yes | From a kosher animal |
| Salmon, tuna, cod | Pareve | ✅ Yes | Fins and removable scales (OU, cRc kosher fish lists) |
| Shrimp, crab, lobster | Pareve | ❌ No | No fins or removable scales (Leviticus 11:10) |
| Catfish, eel, shark | Pareve | ❌ No | Wrong scale type or no scales (OU, cRc) |
| Pork | Meat | ❌ No | Split hoof but does not chew cud (Leviticus 11:7) |
Check Any Fish with KosherFish
When you know the rules, the practical question becomes: is this specific fish on the permitted list? The KosherFish lookup tool on the homepage lets you type any fish name and get an instant kosher verdict. The full kosher fish list covers 291 species with individual verdicts. You can also download the KosherFish app for iOS or Android to check any fish at the fish counter or on a restaurant menu, right from your phone.
The Bottom Line
Kosher dietary laws organize food into three categories (meat, dairy, and pareve), forbid certain species entirely, require proper slaughter for permitted animals, and mandate certified supervision for processed products. Fish is pareve and subject to its own rule: fins and removable scales, as spelled out in Leviticus 11. Most common eating fish are kosher. Shellfish, catfish, shark, and eel are not.
For anything specific to fish and seafood, the KosherFish lookup tool is the fastest way to get an answer. Browse the full kosher fish list, read more on what makes a fish kosher, or check our guide on whether fish is pareve. For any fish you encounter in a store or on a menu, the KosherFish iOS app and Android app give you the answer on the spot. When in doubt about a specific product or community custom, ask your rabbi or check with a recognized certification agency like the OU or cRc.