This is a discussion on Why did my oto die? within the Catfish forums, part of the Freshwater and Tropical Fish category; -->
How long has this tank been running? An established tank is one that is completely cycled and always has constantly stable water parameters: http://www.tropicalfishkeeping.com/freshwater-aquarium/established-tank-after-cycled-40380/#post356380
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How long has this tank been running? An established tank is one that is completely cycled and always has constantly stable water parameters: Established tank after cycled
See Bryon's post in the linked thread.