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Is it cruel to keep the fish in the dark?
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Author:  Ladyd [ Apr 17th, '09, 09:57 ]
Post subject:  Is it cruel to keep the fish in the dark?
Hi everyone,

My partner and I would like to set up a new, bigger system than our first backyard aquaponnics system. We're thinking of a tank a couple of meters in length now - sort of a a medium sized set up. My partner who is really into Aquaponics says that the best thing to do is to not let any light hit the tanks, to minimise basteria growth. So that for our first system we've had to keep a lid on the tanks to stop afternoon light - which means the fish are in near darkness alot of the time.

My question is ... is this cruel? Or do fish prefer to hide away in dark spots in a river anyway? I just want to get some opinions before we start building a phase two setup :)

Thanks everyone....

Ladyd
Author:  Dufflight [ Apr 17th, '09, 10:03 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
Pitch black all the time might be a little too much. A small amount of light so they can tell night from day is better. My salt water tank has a day night light cycle so the fish don't get stressed.
Author:  RupertofOZ [ Apr 17th, '09, 10:30 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
Shading the tank to prevent algael growth is recommended LadyL....

And as you say... in a natural environment... the fish will at times seek out a darkened place under shelter... and so it is in a tank...

To blacken it completely... may impact on the fish... would certainly increase the likelyhood of problems with gaseous interchange to the tank... O2, CO2, ammonia, chlorine etc...

And you could stress the fish when opening the tank cover... and suddenly spooking them with light....

So... some light, shaded... would be the preference...
Author:  grunta [ Apr 17th, '09, 12:46 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
Hi Ladyd, just wandering why you want to stop the growth of basteria?

just wandering because I thought it helped with plant growth and to healp strip nutes from the water?

I used to scrub my fish tanks periodicly to get rid of the unsitly growth but now i just wipe the sides with my hand to dilodge any gunk thats loos and scrub the bottom so i can see the fish better and keep an eye on what is building up on the bottom like any uneaten food

Cheers.
Author:  tamo42 [ Apr 17th, '09, 12:57 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
I think she is actually talking about algae. Algae blooms can play havoc with the pH and DO levels in the water throughout the day, causing huge swings in both. This rapid fluctuation can stress fish and leave them open to opportunistic infection and possible death.

The bacteria that grows primarily in the grow beds are what transform the suffocating ammonia into plant food nitrate. There are some bacteria in the fish tank water, but it's easier to think of them as residing in the grow beds.
Author:  steve [ Apr 17th, '09, 17:12 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
most animals will get into trouble with out a day/night perception.

you will find that one your system matures and gets on in the years, you wont really have that algae bloom, even in summer.

for the moment keep it well covered, but give them a sense of day/night, fresh water mussles are great at filer feeding the algae.i think it was nocky that had before/after pics
Author:  TCLynx [ Apr 17th, '09, 22:08 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
My fish definitely seem to like things well shaded. That is not to say sealed up completely with absolutely no light infiltration but I keep my tanks well shaded. Fabric or high % shade cloth attached to the cage or netting cover over a tank not only helps keep light out, it will help keep jumping fish in the tank. Such a cover also reduces leaves clogging up the system and plumbing.
Author:  johnnie7au [ Apr 17th, '09, 22:52 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
Is it cruel to keep the fish in the dark?

Well ....

I tell my fish everything! :lol: :lol: :lol:
Author:  Ladyd [ Apr 18th, '09, 04:12 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
Thanks everyone. I feel much more informed. Say... here's a dumb question... in our old tanks we had a sort of green bloom along the sides of the tank. It looked like algae ... is that a bad thing? Or does it represent a stable system? There was nothing floating in the water, it was clear usually, with the usual amount of floating particles....


Also, Jonnie7au... I admire the relationship you have with your fish. I too want full disclosure - so I bought a book to help me. "Men are from Mars, Women are from Venus, and Fish are from Watery Places"
Author:  steve [ Apr 18th, '09, 12:10 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
my tank grow varying degrees (depending on season) of that string algae attached to the sides of the tank. i happily leave it there. if it goes really bonkers and starts forming a floating mass then i skim / pull the extra bits off and put it in the worm farm.

i figure its probably growing due to excess nutes so im happy to let it export them :) no doubt it also form a refuge for some biological beasties too :)
Author:  grunta [ Apr 18th, '09, 16:14 ]
Post subject:  Re: Is it cruel to keep the fish in the dark?
the growth on the side of the tank is not a bad thing as mentioned it can strip nutrients and can be grazed by some fish like silver perch, some times it can be filamentous algae or bio film, in my fish tanks it is bio film and beard weed.

i think clear water is a reasonable indicator that your system is balanced but clear water isn't necessarily good for fish growth but having said that i keep the water clear so i can see what's happening in there but would like to try a green water system to grow silver perch or similar fry.

have seen s/perch the same age as mine that were pond grown in green water and they were 10 times larger than mine!
I know that green water in a fish tank would be quite different to a pond but I think it's worth the experiment.
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