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Okay, here's my problem... I've noticed that any time that I reduce the light in my 55 gal tank, I wind up with a dead fish in the morning!
I've tried turning off all the lighting - and even tried just turning off half... Yet the same thing occurs!
Naturally, the solution was easy enough - I simply don't turn off the lights... and have no dead fish!
I'm just wondering if anyone else has experienced this oddity.... Or if anyone would have an educated guess on why this is occurring?
Okay, here are the specifics.... First of all, my entire tank is stocked with ONLY peaceful fish - platys; gold tetras; glowlight tetras; silver hatchet fish; corys; and rasbora hets... Secondly, they are well fed - both flake and frozen... I've tried turning off the lights when all fish have been well established to the tank thinking maybe any newcomers might have died out of shock or something.... But nothing I do seems to matter.... Sometimes the fish is just floating at the top, sometimes stuck to the filter - no particular pattern.... And the weirdest thing about this is the fact that I only lose one fish at a time - and different types (a platy here, a tetra there, etc.).
If it weren't for the fact that the deaths don't happen when the lights are on - I'd think it was a tank problem... I've even thought perhaps the lights might provide additional needed heat - but the temp has remained the same so I know that my heater is working correctly....
What a puzzle! Any ideas or similar experiences?

To thine own self be true...

Do you have live plants in your tank? Live plants will consume oxygen when there is not enough light for photosynthesis causing the dissolved oxygen in your tank to drop when the lights go out. If this is the case you can take measures to increase aeration to keep levels of O2 higher.

Do you have live plants in your tank? Live plants will consume oxygen when there is not enough light for photosynthesis causing the dissolved oxygen in your tank to drop when the lights go out. If this is the case you can take measures to increase aeration to keep levels of O2 higher.

Live plants don't play a big role in O2 in tanks. It is close to immpossible that the plants will consume all the O2 from the tank. I have plants and I even inject CO2 in my tank

That is sure a odd one dreamweaver are ur fish photosynthetic fish??

Gee

!!I think I just learned somthing new!!

What kinds of fish are you finding dead? Also, how many fishies do you have in there? That could easily play a role.

Inky

BigGee,
Actually with heavy Co2 tanks when the lights go off the plants can consume so much O2 that fish may gasp for air at the surface.


"A noble spirit embiggens the smallest man" Simpsons

Actually with heavy Co2 tanks when the lights go off the plants can consume so much O2 that fish may gasp for air at the surface.

Hmmmm I've never heard abt that or experienced or saw that....
If so...dreamweaver is ur tank heavly planted or heavly injected with CO2?



Gee

!!I think I just learned somthing new!!

Yah biggee all plants consume O2 at night because they are not photosyntesis because no light. I agree the tank would have to be heavily planted and prob overloaded with fish too. ( this is also one of the reason in a lake that ices over you can have a large winter kill).

No plants at all just decorative hidey hole accessories (I've had 2 serious bacterial infestations in years past, and by eliminating the plants - live and artificial - haven't had the problem of bacterial deaths since) ... And as I said in my original post, the species that die vary - not just one type of fish... ????????????

To thine own self be true...

It may be that the temperature drops drastically in your tank when your lights are off?

Can you post a piccie of the whole tank? It might help us spot something. Post water perameters, and give details of the bacterial infection if you can, and what treatment you used for it. Its not usual for fish to succumb to bacterial infection when they sleep as it slows down their metabolic rate, thusly making them less active in combatting illness. Perhaps the original ailment persists?

Its worth mentioning your fish species and the brand and intensity of the lights you use, sometimes fish succumb to photoshock (ie bright illumination going off suddenly or coming on the same way). Its also worth checking your electrical equipment, if any wires or unsealed light fittings are causing surges the tank could concievably be getting shocks when things start up or go off. Sometimes all it takes is a little bit of condensation to make that electrical connection, and when the lights go out and if the tank water is heated there will be a lot of evaporation as the air above the tank becomes cooler than the water.

Lastly is there anything happening in the house, particularly at night that could cause pollutants to enter the water? Does anyone smoke profusely near the tank, use air fresheners, joss sticks, plug in scents or deodorants near the tank? Any loud noises , bright flashing lights or similar that would be more visible to the fish when their lights go out?

I once had a friend who lost fish during the night because he had a certain species of catfish that went aggressive only at night. Any potential species for doing that? Species like knifefish are famous for not showing their crimes in the light of day.

I cant think of anything else !

When youve eliminated the impossible, whatever remains, however improbable, must be the truth . ( Arthur Conan Doyle - via the lips of his most famous creation - Sherlock Holmes.)

The previous bacterial problems are long gone -- The second time they occurred, I lost all fish... Completely drained the aquarium. Scrubbed the tank, glass discs, and decorations with a mixture of water and Pima Fix. Refilled the aquarium and let it sit empty for a month or so. Then I drained it once again and refilled... Eliminated the live and artificial plants, waited until my water tested within safe parameters (having my lfs check it) before adding fish... Haven't had any apparent bacterial deaths since....
As far as the lighting goes.... well, I use the lights that came with the aquarium.... Two 15 watt - one in each hood.... As my thermometer shows no influx when the lights are turned on or off and as there are no unsealed lights or wires - I assume all items are in correct working order....
As I've said before, ALL fish in the tank are peaceful species --- rated A by my lfs.....
Although I don't test the water myself, my lfs has assured that my water is well within safe parameters....
Sooooo... I suppose it's not the worst thing in the world to have to leave the lights on 24/7.... Still, it would be nice to understand why it's necessary to do so.... ?????
Following are pics of my tank... You'll note that I use a pretty solid, non-descript background -- because I love to see the beauty of the fish themselves, and find most "normal" backgrounds way too busy and distracting!

Attached Image:


To thine own self be true...

Just another shot... Yes, there are a lot of fish --- but they thrive - well, at least as long as I keep the lights on!

Attached Image:


To thine own self be true...

Leaving the lights on won't work forever. Fish need time to sleep and if the lights don't go off they don't sleep and eventually they die. Are the room lights on after the lights go off? When the tank is brighter than the room the fish can't see out as well but when the room is brighter than the tank it's very easy for them to see out and some fish will panic at even the tiniest movement near the tank. You also have practically no resting or hiding places so it could be they are stuck in the open with commotion around their tank or they have nothing to rest against when they sleep. Although it looks like you have a small enough filter on a 55g and the fish in the tank should be able to handle that kind of flow without objects to break it up. I've never set up a tank that bare though and at night mine are always resting in the plants away from the water flow.

Can you post any water parameters? ammonia, nitrite, nitrate, ph, etc...

!

If you turn the lights on in the morning suddenly (as in the first thing or near the first thing in the morning), the sudden brightness can be enough to shock fish. My ichthyology prof told us that she had accidentally killed many fish that way in a fisheries setting . Next time you turn out the lights, turn on other lights in the room and leave them on for at least 15 minutes before you turn the tank light on.

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Yep, having seen the tank now id definately say the sparse decoration in the tank is making the photoshock issue more of a problem. Get a load more bogwood and some large real plants and floating plants and weeds in there to provide a lot more cover and break up the light. If you can, modify the lights to make them come on sequentially within about 10 minutes of each other. I think your fish are feeling exposed.

Snooze ,snooze, AAAARRRRGHHH! My retina's hurt!

You might find a setup like this a bit more appropriate for your fish.

http://i12.photobucket.com/albums/a245/longhairedgit/IMG_3902.jpg

Well, ok you dont have to go quite that overkill on the plants, and obviously its a blackwater setup for light sensitive tetras, but the amount of cover and black gravel should show you how far some of us will go to ensure that the fish are not stressed. For some catfish etc some people run even darker setups than that.

I'd rather have happy fish and not always be able to see them, rather than risk their health for an aesthetic preference,besides its one of those odd things, when you provide cover , the fish tend to be less shy of you. But if you go heavy on the plants, just dont choose green fish .lol. The background itself doesnt have to be that dark, but as long as you have cover with some noticeable shade you may not have to change it to being darker than it already is. The background as it is, and no cover is a problem. The contrast for viewing would still be there even if you had rocks covering the entire background, as long as the colour is different from that of the fish.

Oddly enough black is a great colour to see the fish against, the only drawback is that aggressive fish will see perfect reflections of themselves and be aggressive with their own reflection for so long it could put them under stress.

HURRAY!!!! I made it through the first night without losing fish!!!! Haven't changed anything in my tank... just merely darkened the tank more gradually than ever before.... Turned off one side of the tank itself.... Waited an hour or so... Turned off the other side, but left a lamp on in the room.... Then turned the lamp off and left a small curio cabinet light on (close proximity to tank) and finally.... turned off the curio cabinet! Observation this morning reveals ---- NO DEATHS!!!! Still don't understand why this procedure was necessary -- but I can certainly be pleased about the results!

To thine own self be true...

Thats cool, when you have the cash alter the decor to provide a bit more cover so you dont have to go through the ritual of turning lights off slowly, and just for reference sake I think its worth anyone with a tank the size of yours and as many fish as you to buy your own test kit and learn how to use it. My experience of LFS water tests to date has been... erm...dodgy. Plus you really need to test your water at least every few weeks.

I'm glad to hear that dreamweaver! I've also learned alot from this post...thx everyone!

kegman wrote:
Yah biggee all plants consume O2 at night because they are not photosyntesis because no light.

I know that

Gee

!!I think I just learned somthing new!!

im new to this but correct me if i shouldnt do this. my tank has a auto timer on it, for me to avoid shocking the fish i put a clear bright light on one side and a darker blue one on the other. i have a small assortment of fish some like the darker some like the light. and when the time comes when the lights go out there usually all sitting over on the dark side to sleep. then when it comes on they're already on the dark side. i think this avoids any shock.
kenny

Im sure that is absolutely fine as a setup, as well as avoiding physical photoshock , using a timer gives the fish a level of consistancy to work with. When they are behaviourally adjusted to expect lights out at a certain time they will begin to prepare for the night in advance of lights out by congregating in areas they feel the most comfortable cruising and sleeping in at night. Fish have incredibly accurate body clocks, knowing when the lights will go and off prior to it actually happening if given a regular schedule.My rainbows typically start warming up for the morning displays about 30 minutes prior to lights on, youll also notice fish like tetras look blanched out if you turn on the lights in the middle of the night, but in the am at an expected time they are always in full colouration when the lights come on, meaning they started the pigmentation change at least a few minutes before. Plecs and catfish often make appearances an hour before lights go out etc. I think if the fish are within sight of a window they will use natural daylight to calibrate themselves against, so for those people who have fish who can see light from outside it may be beneficial to sequence your lights to change with the seasons.

I think its allowing them the predictability of a regular photoperiod that they can stick to that helps combat photoshock on a psychological level. It gives them a chance to mentally prepare. I think people with timers really do have an edge in fishkeeping over those who dont.Especially when the lights are sequenced to come on gradually.

Many thousands of creatures regulate themselves in this way, its not unique to fish, birds will do it, and some reptiles positively depend on it, having a pineal eye that helps them analyse even subtle changes in light quality,giving them some indication even as to the season and their longitute, latitude and elevation on the earths surface .Fish however with their excellent colour vision (in diurnal species) and some whose eyes are seriously sensitive to light including frequences we cant see ourselves (infra-red and ultra - violet) like most nocturnal fish, have no need of such specialised organs as pineal eyes, and can detect the subtlest changes in light with no special effort. Small wonder they are susceptible to light blindness. Not having true eyelids is always a bit of a problem when folks shine high wattage fluorescent and metal halide bulbs at you.