how to tell if fish preg

Question
i have a tropical aquarium with 2 algae eating sucker fish recently one of them is getting really big on the belly area but it is has also appeared with red mark similar stretch marks i don't no if it is pregnant or if it is something more serious

Answer
Hi Katie,
  Plecostomus catfish (what you are called sucker fish) do not get pregnant as such. They lay eggs. The female will lay the eggs in a hollow tube (a hollow log in nature) or in a cave and then the male will take care of them.   She should not have any red marks on her.  That might indicate that she scrapped her belly on something.

-- Ron C.
  rcoleman@cichlidresearch.com
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