TempoLife › Features › Fish: minimum sizes, closed seasons and eating advice
What you catch, and how often you should eat it
What you catch and what you should eat of it: 20 Baltic and inland species with the national eating advice for each, why it applies, the rules that matter when you catch it, and what the kitchen changes. Legal sizes and seasons change yearly, so the pages point at the rule and its source instead of printing a stale number.
This is a reference page, not a fishing licence and not medical advice. Minimum sizes, closed seasons, bag limits and licence prices are set per country and per water body and change most years, so no number for them is printed here — each species page says which instrument sets the rule and where to look up the figure for the water you are standing on. If a clinician has given you a fish frequency or a contaminant instruction, that instruction outranks anything on this page.
How to read this
The species are grouped the way the national advice itself groups them, because the advice is not one list but several, each written for a different risk. The predators are the mercury group: fish that eat fish, for years, in inland waters. The fatty Baltic fish are the dioxin group: wild fish of the Baltic food web. The lean sea fish are low in everything the advisories care about. The low-concern fish are the ones the "two to three fish meals a week" recommendation is built on, and the cyprinids are the abundant, underused catch of the inland waters. Shellfish sits in its own group because its rules are about gear and disease, not contaminants.
Each species page carries four things: where the fish lives, why the advice says what it says, the advice itself with its source, and the rules that apply when you catch it — sizes and seasons described by their instrument rather than printed as numbers. Fish is the main dietary source of vitamin D, and the nutrition rows linked on each page are the same USDA FoodData Central figures the rest of this site uses.
Freshwater and coastal predators
the mercury group
| Species | The advice in one line | Concern |
|---|---|---|
| Pike | Not in pregnancy at all; one to two meals a month for everyone else. | Mercury |
| Perch | Small perch is everyday food; large inland perch is limited for children and in pregnancy. | Mercury |
| Pike-perch (zander) | Limited for children and in pregnancy where it comes from inland waters. | Mercury |
| Burbot | Limited for children and in pregnancy; the liver deserves its own caution. | Mercury |
Fatty Baltic fish
the dioxin group
| Species | The advice in one line | Concern |
|---|---|---|
| Baltic herring | Small herring freely; large herring over about 17 cm is limited for young people and in pregnancy. | Dioxins and PCBs |
| Salmon (wild Baltic) | One to two times a month for young people and in pregnancy; farmed salmon is a different fish for this purpose. | Dioxins and PCBs |
| Sea trout | The same Baltic fatty-fish reasoning as salmon; heavily protected as a fish. | Dioxins and PCBs |
| European eel | The fattiest fish here and a critically endangered species — an occasional delicacy at most. | Dioxins and PCBs |
| Baltic sprat | A short-lived oily fish; no size-based advisory of its own. | Dioxins and PCBs |
| River lamprey | A very fatty river fish sold as a seasonal delicacy; treat it as one. | Dioxins and PCBs |
Lean sea fish
| Species | The advice in one line | Concern |
|---|---|---|
| Cod | Lean and low in mercury; the problem with Baltic cod is the stock, not the fillet. | Low concern |
| Flounder | A lean bottom-feeder low in the food chain; watch for local harbour advisories. | Low concern |
| Garfish | A spring visitor with alarming green bones that are entirely harmless. | Low concern |
Low-concern fish worth eating more of
| Species | The advice in one line | Concern |
|---|---|---|
| Whitefish | Moderately oily but low in the food chain; no frequency advisory. | Low concern |
| Vendace | Small, short-lived and plankton-feeding — about as low-risk as fish gets here. | Low concern |
| Rainbow trout (farmed) | Farmed on controlled feed and harvested young — the oily fish with no advisory attached. | Low concern |
| European smelt | A short-lived spring fish that smells of cucumber; nothing to limit. | Low concern |
Cyprinids and underused catch
| Species | The advice in one line | Concern |
|---|---|---|
| Bream | Abundant, low in the food chain and almost nobody eats it — the bones are the reason. | Low concern |
| Roach | The most abundant fish in most lakes and the least eaten; low in the food chain. | Low concern |
Shellfish
| Species | The advice in one line | Concern |
|---|---|---|
| Noble crayfish | Lean and low-risk to eat; the real risk is what you carry between waters. | Low concern |
The other half of the page
What a fish costs you in the kitchen is the part of the advice most people never read. Freezing the catch before eating it lightly cured is a legal requirement for fish that will be eaten raw, the cure is what turns a fresh herring into a salt question, and smoking adds compounds of its own. The home preserving pages cover the methods — freezing, curing, smoking — with the ratios and temperatures that make each one safe, and this page links the two sides of the same fish together.
Eating advice: Finnish Food Authority and Swedish Food Agency national advice on Baltic and inland fish. Contaminant ceilings and the Baltic derogation: Regulation (EU) 2023/915; weekly tolerable intakes: EFSA methylmercury (2012) and dioxins/dioxin-like PCBs (2018). Nutrition figures: USDA FoodData Central rows published on this site. Checked 2026-09-06.
Frequently asked questions
Is Baltic fish safe to eat?
As a category, yes — and as a category question it is the wrong question. The national advice is written per species and per size, because that is where the differences are: a small herring and a large one are the same species under different rules, and a lake pike and a sea flounder share no contaminant story at all. The fish that carry frequency limits are the long-lived freshwater predators (mercury) and the large, fatty Baltic fish (dioxins and PCBs). Everything else is the fish that the general "two to three fish meals a week" advice is built around.
Which fish carry the mercury limit?
The freshwater and coastal predators — pike first, then large perch, zander and burbot. Methylmercury builds up along the food chain and with age, so the fish that eat fish, for years, in waters where mercury settles, are the ones the advice limits: for children and in pregnancy the big ones are off the menu entirely, and for everyone else they are a one-to-two-meals-a-month fish. A small perch from the same lake is everyday food.
Why are fatty Baltic fish limited when farmed salmon is not?
Because of where their fat comes from. Baltic herring and Baltic salmon spend years eating from the Baltic food web, where dioxins and dioxin-like PCBs — left by decades of industry and paper bleaching — still circulate and concentrate in fat. Farmed salmon eats controlled feed and is not part of that chain. The derogation that lets Baltic fish be sold is written into the EU contaminant regulation precisely because the fish is caught wild in those waters; the national advice limits how often children, young people and anyone pregnant should eat it.
Does cooking remove the contaminants?
Mercury: no. It is bound in the muscle protein and no preparation removes it — the only controls are species, size and frequency. Dioxins and PCBs are fat-soluble, so trimming skin and fat, and cooking in a way that lets fat drip away, removes a share of them — but the share is partial and the advisory already assumes you are eating the fish as people actually cook it. Preparation changes what is on the plate; it does not rewrite the advice.
Where do I find the actual size and season limits?
With the authority that publishes them, not on a website like this one. Minimum sizes, closed seasons, bag limits and permit prices are set per country and per water body and are amended most years; a printed number goes stale and a stale number is worse than none. Each species page below says which instrument sets the rule for that fish and where the current figure is published.
Log the catch, not just the memory of it
TempoLife counts the fish you ate against the same nutrition database linked on every species page — and your omega-3 and vitamin D come from what you actually logged, not what you meant to.