Needlefish

Just curious if anyone can help me differentiate between a Houndfish and an Agujon? There are a few differences listed on biogeodb.stri.si.edu, however they seem fairly minute... Other than one being "relatively slender" and the other "relatively robust", does anyone have a tried and true method? I'd like to be able to know which it is, when I see one swimming by. Thanks in advance, Jeff

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