Suppose you placed a fish, a goldfish for example, into milk instead of water. How long could you expect the fish to survive?

Would it die due to lack of oxygen? Is there any other factor that could cause the death?

  • $\begingroup$ Why not a trout? $\endgroup$
    – jamesqf
    Commented Dec 5, 2016 at 20:30
  • $\begingroup$ I am voting to close this thread because no previous research attempt is shown. You can't just come, ask a three line long question as if you were on the net. This goes against this forum's strict rules $\endgroup$
    – Algae
    Commented Nov 26, 2019 at 15:01
  • $\begingroup$ @Algae — Unfortunately, in practice, you can't vote to close until you have more points (aka reputation). But I did it on your (and my own) behalf. However it's an old question, and, like the goldfish, dead by now. $\endgroup$
    – David
    Commented Nov 26, 2019 at 17:48

1 Answer 1


I can't support this answer with scholarly articles. But it's an interesting question if you think of milk as highly polluted water.

Water from a tap (which is what goldfish usually live in) is 'fairly pure', with the naturally occurring minerals sodium, calcium, magnesium and potassium respectively in highest concentrations (varies by location.)

Milk, on the other hand, has not only a much higher mineral content, but also has fat, protein, carbohydrates, and white blood cells as 'pollutants'. In fact, whole cow's milk is only ~87.8% water.

Looking at calcium alone, the concentration of Ca in water is about 3 mg per 100cc, or .003%. Milk has .13% Ca, or 130 mg per 100cc. Since Ca is a major player in nerve and muscle function (in humans, a very relatively mild increase in serum Ca causes tetanic contraction of muscle), my guess is that the poor little fish would not be able to maintain normal serum Ca levels for long. It would die of inability to move fluid over its gills, that is, it would suffocate even in the presence of dissolved oxygen. Not to mention that the gills would also be coated to some extent by fat (3.5%), protein (3.8%) and other 'gunk'.

How long would it last? Probably not more than a few minutes.

  • $\begingroup$ Thanks for the answer. Now I can do some more reading about the effects that the presence of these minerals have on fish. $\endgroup$ Commented Dec 5, 2016 at 23:27

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