But the population plunged in the smallest fish species, the fathead minnow.

ECONOMIST: Human contraceptives are bad for fish

After two years of treatment, the fathead minnow population collapsed.

ECONOMIST: Human contraceptives are bad for fish

You can enter to win a dry erase calendar set (or other funky design) found here at WallPops (no Fathead or Euro for purposes of the giveaway due to license restrictions).

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Meanwhile, aliens including fathead minnows, channel catfish and common carp, which would have been hard put to survive in the savage waters of the undammed canyon, have moved in.

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