# Light sensitive fish



## kgtoaks (Mar 13, 2010)

Today I added 6 Rasbora Heteromorphas to my 20g. After drip acclimation, I added them to the tank with the lights off to reduce stress. They seemed to behave normally until a couple hours later when I turned on the light. They immediately began darting around the tank and ultimately took refuge bunched up very tightly under my underwater filter (co2 diffuser) intake. This behavior did not change for a couple hours, so I shut off the light again. Once the light was off, they were schooling in the middle of my tank peacefully.

I have been keeping fish for years and have never come across this type of sensitivity to light. I read that these fish prefer subdued lighting (after purchase) and I worry that I am causing them dangerous amounts of stress. Fish torture is not my thing.

Lights are 2x24w T5HO, 6700+10000 and the tank is moderately planted.

Have any of you come across similar behavior? Will they make it until my tank has grown in? Should I go with a different species?


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## Diana K (Dec 20, 2007)

IME they will acclimate pretty well to a well lit tank, but not the same day as they are purchased. Leave the light off the first day, then allow natural light (dawn) to happen the next morning, then turn on the tank lights. 
If the room does not really have natural light, then turn on the room light (overhead, desk... whatever is not tank light) for a few minutes or half an hour, then turn on the tank lights. 
If you can turn them on independantly that would be good. An hour with one, then most of the day with both on. 

Many fish do not want to be out in the open in the streams or lakes they come from. Predators are out there. Fish prefer to hide in the plants and tree roots that are around the shore. It is darker there, so predators will not see them. To communicate with the rest of the school they will brighten their colors. 

So:
Take it easy turning on the light. Try to mimic a natural dawn. 
Accept it that these fish will be a bit shy until there is more plant growth, but they will get better pretty soon. 
You cannot expect them to be right out front from the first day.


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## kgtoaks (Mar 13, 2010)

Thank you Diana. It seems I was expecting too much on the first day. The room is fairly well lit early in the morning, which will help.

I wish I could configure the timing for those bulbs independently. Guess that is why some people pay the big bucks.


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## SirKappa (Apr 19, 2010)

Maybe you can try some kinds of floating plants to help dim out the light? most stem/bunch plants will grow floating, or you can get something like duckweed? However the duckweed can quickly take over the top of your aquarium and you will forever be netting it out.

Just a suggestion. Hope this helps!


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## kgtoaks (Mar 13, 2010)

The floating plants are a good suggestion for shade. They also tend to be a nice aesthetic addition to many tanks I have seen. I just don't want to cut any of my plants off from a decent supply of light since they are all doing well.

After a few days, the rasboras seem to be slowly accepting their bright home. My swords and ludwigia are growing quickly and provide a decent shaded retreat. In a month everything should be very filled in.

There seems to be a lot of fin nipping going on. Hopefully this isn't going to be the case in the long run. I have done semi and aggressive tanks and I want something soothing. Do you think a lack of females could be my problem? I think I only see one.


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## Diana K (Dec 20, 2007)

Total lack of females would be better than just one. One reminds them of what they are missing, and they all want to gang up on her. Get more females to spread out the chaising.


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## DarrylR (Dec 5, 2007)

If you are going for floaters, water lettuce is a good choice. It doesn't clog up the surfaces as much as say duckweed, and very easier to manage.


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