Can lights be too bright? Anything I can do to dim them?

[swifty]

I have a T5NO Aqueon strip for my 4 foot tank. It is a 3 foot strip, so depending on where I place it, it covers only 3/4 of the tank. The other day I moved it to the extreme left side of my tank, and have noticed all of my fish (silver dollars, JD, convict, firemouth) have moved to the right side, out of the direct light and generally spend most of their time there. Anytime they go on from the timer everyone scatters and huddle in corners for 5-10 minutes before retreating to the right side.

If I place it in the center, they just go to the left/right sides.

I have a spare T8 fixture, but it is only 30", so it has a 24" bulb. Anyone with an experience like this? Are my lights too bright, or will they adjust to them over time?

 

[swifty]

Ok well, looks like they really can be too bright.

I put that T8 fixture on to experiment, and after 15 or so minutes of them hiding, they're all out in the open. Swimming back and forth, across the tank, cruising around. Looks like I'll have to find a T8 that can fit the entire tank now.

 

[xraycer]

In my experience (and opinion), fish hates bright light.........it only appeals to us. Both prey and predatory fish feel safer and prefer to be under the cover of shade/dimness a majority of the time, whether its to hide from larger predators or for ambushing prey.

Any reasons you're set on fluorescent lighting? LEDs are now super bright, drastically come down on price, and gives a more natural lighting effect to the tank. Plus, they are cheaper to run in terms of electricity. My friend bought a few of these LED strips from this EB vendor and the lights were bright, but not overly bright http://www.ebay.com/itm/48-58-LED-L...Fish-Tank-White-Blue-Extendable-/251614533802

 

[Aquanero]

Unless you're trying to grow plants, fish perfer subdued lighting. I have LEDs with floating plastic bamboo to breakup the light. In my BGK tank I have actenic lighting so I can see it come out other wise it spends all day in a log. I also do not run lights the full length of the tank and only light about 3/4 in the center leaving the sides darker so the fish can move in and out as they wish.