Its fish semen. This is nothing new and is/has been done around the world for who knows how long. If you eat a lot of fish you have probably had some and just did not know it.
I rarely eat fish but indeed do and never eat semen. This is a you problem, I know how to gut a fish.
Not saying you don't. Just saying that mass produced or canned fish as well as some store bought fish will likely contain "byproducts".
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