Cory's and fluorecent bulbs - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 3 Old 06-05-2010, 12:34 PM Thread Starter
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Cory's and fluorecent bulbs

My little aqueon mini bow came with a ten watt incadescent bulb. I replaced it with a small 10 watt fluorescent. I notice whenever I turn the light on now with the fl bulb, my coreys flip out. They dart around the tank all frantic. They settle down in a few seconds. They never reacted this way when I had the tungsten bulb. I know coreys like dark, so is the light too harsh for them?
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post #2 of 3 Old 06-05-2010, 07:58 PM
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That's possible. Corys do not like bright light period, so the less light over the tank, just what is sufficient for the plants if you have any, is best. Floating plants help to diffuse overhead light. The CF bulb is better light and produces less heat, so I would keep it, and consider floating plants if you think it is bright.

More likely the issue is the sudden change from dim to light and vice versa. No fish likes that. There should always be light in the room (whether daylight or a lamp or two) when the fish tank light comes on and goes off. This makes a big difference in how the fish react. Having light in the room is closer to the natural dawn and dusk periods that all fish are accustomed to. If you've ever been suddenly awakened at night with bright light, you know what that's like; it's worse for the fish as they can't close their eyes, and it startles them, they panic, and frequently crash into the walls or jump into the lid (or out if no cover). Not good.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #3 of 3 Old 06-05-2010, 08:19 PM Thread Starter
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That makes total sense. Thanks for the suggestions.
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