Butterfish
Best avoided during pregnancy — fish sold as 'butterfish' (especially at sushi restaurants) is very often actually escolar, which causes digestive problems that aren't worth risking while pregnant.
Cross-checked against NHS guidance
This one is mostly a labelling problem. True butterfish (Peprilus) is a small, genuinely safe fish, but the name 'butterfish' is very commonly used — particularly on sushi and restaurant menus — for escolar, a completely different fish that's sometimes also sold as 'white tuna' or 'super white tuna'. Escolar contains a wax ester that the human body can't properly digest, which can cause keriorrhea — an oily, urgent digestive upset — in some people even outside pregnancy; it's actually banned from sale in several countries for this reason. Because there's no reliable way to tell from a menu or a fish counter which fish you're actually being sold, the simplest and safest approach during pregnancy is to avoid anything labelled 'butterfish', 'white tuna', or 'super white tuna' altogether, rather than risk a GI reaction on top of everything else pregnancy already throws at your digestive system.
What to be aware of
- Avoid anything labelled 'butterfish', 'white tuna', or 'super white tuna', especially at sushi restaurants — it's very often escolar.
- Escolar's wax ester content can cause significant digestive upset, which isn't worth risking during pregnancy.
- There's no reliable way to visually distinguish escolar from true butterfish once it's filleted or served.
Safe substitutes for Butterfish during pregnancy
If you're craving butterfish but it's off the menu for now, these are safe swaps that still feel like a proper meal:
- Salmon or tuna sushi — Stick to clearly labelled, well-known fish at sushi restaurants where the species isn't ambiguous.
- Tilapia or basa — Mild white fish with no digestive risk, easy to cook simply at home.
US guidance
The FDA has issued specific warnings about escolar sold as 'butterfish' or 'white tuna' due to the risk of keriorrhea, recommending it be avoided rather than portion-limited.