Thanks the replies. I've been away over the weekend and only had time to read them now.
The thermostat will only stop the heater heating the water to 24 degrees. The pc will keep on heating it and you will end up with dead fish. Sorry but i am not a fan of these things. The temps will be all over the place when it should be constant. 6L is a ridiculously small amount of water and will not help at all with water stability. The larger volume of water you have the more stable the conditions (temps/nitrite/nitrate etc) will be. 13"x4.5"x8.75" is a joke. If you want to keep fish then go and buy a proper tank.
I appreciate the tank is small, however I did consult the aquarium shop before going ahead. I even took in a 1:1 scale cardboard model of how it would look so they would be sure. I was told I could keep a lot more fish in there but I don't intend to go above 5. According to various stock calculators the tank is big enough for fish this size. I am keeping a close eye on them and they do not seem distressed. I assure you I am a lover of all animals and if I thought this was in any way cruel I would give them a better home.
They are lyretail guppies if i am not mistaken. Tropical fish need a constant temperature of between 23 and 25 degrees although this varies between species. A tank in a computer is going to go way above that. Water is a good conductor of heat which is why watercooling exists. The inside of my case is usually a minimum of 26 degrees and that's with 5 fans. Fish tanks in a pc are a ridiculously bad idea. Probably against the cruelty to animals act as well. It is also widely accepted that a fish tanks should'nt hold less than 10lt of water. Was the tank even cycled?
I will not be using the computer a lot (if at all now). I was going to get rid of my laptop and use this instead, however the spec isn't that great and a step down from what I'm using already.
The water was treated for 10 days before I added fish and correctly cycled. Ammonia is 0 and nitrite levels are 0.25 appoximately. Just about to do another test after this reply actually.
When did you think to do this?
Joked about the idea years ago. When I saw a piece on the Overclocked Orange (and case modding as a whole) I decided to go ahead and see what was required, turned out not a lot so I did it.
Wow that looks really good. Nice work

. How are you dealing with the condensation that comes out of the tank though as that could cause a problem? :S
I made a condensation lid that fits over the tank, all fish tanks have them to some degree.
How much would you charge to make me one
I'm not sure I could charge to be honest :s There's the matter of electricity and water being about 5 inches apart. I'll do a full run through as I kept a journal when I was building it.
wow really liking the look of this, did you make the mini fish tank yourself or get it made somewhere?
Local aquarium shop made it for me. In theory it isn't too hard to make yourself but for £22 it was worth getting someone who knew what they were doing to make it.
Also, where does the HDD go? Whenever I've seen it in a case its in the lower front section.
HDD is stood upright next to the motherboard. It's worth mentioning it is on rubber feet to reduce any vibration getting to the fish tank.