Fish With No Natural Sunlight

[Colin_T]

In that case why does every single fish book (setup) say not to have fish tank near windows or in direct sunlight? i know about algae but surely it cant make much diffrence on the fish to not have much sun.

To prevent tanks from overheating in warm climates and from having cold air getting on them in cold climates. Glass windows are not very good when it comes to insulation. Double and triple glazing helps but not everyone has that. By having the tank away from the window you help to limit the outside temperatures from affecting the tank temperature as much.

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B- Sunlight, both indirect and to a lesser extent direct - even if given prolonged amounts of time - cannot sufficiently raise the temperature of a tank to cause problems. A tank would need to be in a window during the hottest part of a day for any detrimental effects to the temperature to occur. 1-5 degrees fluctuation in temperature can be tolerable to most fish, especially when it's a gradual increase and decrease.

That theory might be fine if you live in a temperate climate. However, if you live in Australia the afternoon and morning sun is pretty hot during the summer months and can quickly increase the water temp by 10C or more in a few hours. And if the weather has been hot for any length of time leading up to then, chances are the tank will already be sitting in the high 20sC or even low 30sC. If you add another 5 or 10 degrees C to that you push fish past their limits and lose entire tanks of fish.
Many parts of Australia regularly hit 40C + (over 100F) in summer and our temperatures are measured in the shade. If you put a thermometer out in the sun during summer they regularly hit 60C+.

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I herd about a goldfish that got no light what so ever and it turned white. LOL

That is common in black moors when they are kept indoors away from bright light. We used to see it in the quarantine room. We would get in a shipment of black moors or panda moors and after a couple of weeks in quarantine they would start to fade. Some of the pandas would go completely white and the black moors would go bronze. If you put the fish out in a pond for a month they would go black again.