lights off?

[ara35]

can i leave the lights off all day in a tank of rosy red minnows that are being used for cycling since i have no other fish in the tank? they are much more active with the lights off because i havent bought too much things for hiding spots.

[Coler]

would you reconsider your method here ?

1) 'used for cycling' is a little harsh. You can do a fish cycle but don't regard the fish as expendable. If you chose this option you really have a responsibility to minimise discomfort on the part of the fish - i.e. large water changes whenever necessary (when ammonia/nitrite is greater than .25ppm, twice daily or whatever it takes). Assuming you're doing this, why not put some cover in there ? It will make the fish less stressed.

2) Get your lights on a timer - fish in aquariums really, really like routine.

3) Leaving the lights off is not especially cruel per se, especially if the tank is in a room which receives plenty of natural sun light. However it sounds to me like your fish need a better environment i.e. more cover. Why not just provide them with this, i.e. address the real cause of the stressed behaviour, as opposed to minimising it/accomodating it ?

[ara35]

are cories, loaches, or gourami hardy enough to stand cycling?

[Star_Rider]

no...cories are sensitive to water conditions and none of the fish you mention should be 'used' to cycle a tank.

danios and white coulds are your best bet for hardy tank inhabitants during a cycle.
I personally advocate fishless cycling unless you have a good source of live bacteria,

if you decide to do a fish cycle..then you should consider daily water changes as needed. to keep the ammonia, nitrites below .25

[Coler]

I don't believe any of those fish would be ideal as they can be quite sensitive, especially the corys, loaches and gourami.

But, basically, the issue is not how hardy the fish is but how diligent you are in doing your water changes. That said, I would not add those fish until the tank was established & cycled fully and when you do add, you will have to add slowly, no more than a couple of fish every week/10 days to make sure the bacteria colonies are not overloaded (when you fish cycle you accumulate enough bacteria to manage the waste from the amount of fish you finish with and no more).

Test twice a day minimum, and do as much changes as necessary to keep ammonia, nitrite below .25ppm. Its as simple and as much of a pain in the neck as that :)

[Mgamer20o0]

fishless is the best way to cycle..... less work no water changes....

as for the lights you can keep them off. lights are there for you to be able to see the tank.