Black Widow Tetras afraid of light?

[Masha]

I've got a 23 gallon tank - I've recently upgraded from a 10 gallon - and my two black widow tetras swim about quite normally when the light is off, but when it's on they each go to a hiding spot under the driftwood and stay there. Just hanging still in one spot. Sometimes I see one venture out, but mostly they hide.

I thought at first that it was because I had the temperature too high - I accidentally set the temperature a bit too hot for them for about a week.

I'm planning to get more black widow tetras, as I know they do better in a bigger group, but I wont be able to add more fish to the tank for about 4 weeks - I've got corys in my quarantine tank for another week, and then the new black widows would be quarantined for about 3 more weeks (the fish shops around here have itch quite often so I don't want to risk introducing them directly)

So my question is - should I just put the lights on and hope they get used to it? They've been doing this for about two weeks now - at first hiding all the time, I think maybe a bit better now.

Or would it be better to leave the lights off? I do have (low light) plants so I don't like leaving it completely off for 4 weeks...

I put the room lights on first, and I wait till there's a fair amount of sunlight before I put the lights on. It's also not a dreadfully bright light, I don't think?

I'm worried they are stressed

 

[The Trooper]

Could you get a bulb that's not as bright perhaps? I know in my new big tank i have 3 light strips all different intensities.

 

[Masha]

I guess so - I think my light is pretty dim as it is. It's a 20 W Extra Day High Glow tube - I think it's a T12

 

[Blitz]

They could just be nervous fish. My 20L has 2 silver Dollars that do the same thing, even as someone passes by the tank they run for cover......banging into everything along the way, but I'm thinking as you stock more, they will become more bold.

the other thing is, and I know it might sound silly, since you recently changed tanks, does the new one have a background of any kind? Backgrounds serve as more of a purpose then most people know, they not only hide the wires and tubes, but it plays on how light in the tank reflects, with no background, the light sometimes (Not always, depends on other room conditions) refracts off both the front and rear glass, giving them a very distorted view of whats going on outside their tank, also very high shine or glossy backgrounds, tend to project, it's image on the front glass.....if nothing else, something to experiment with to see if anything changes.

 

[Canary bird]

Have you thought about making a diffuser for the light , that's what I did, all my fish freaked out with the light on so I got some curved plastic put slices/vents in it and 2 clips to clip on the tube, it worked a treat , I sold the tank years ago and the owner (my friend) still has it on the light and now I have LEDs in all my tanks and all my fish are great,

 

[Masha]

Blitz - the tank has no background at all. I wonder if that makes a difference.

Canary bird - thanks for the suggestion. A diffuser might work - there's not much space under the hood but I could see what I can do...

 

[Rivercats]

Many tetra's don't like a lot of light. In my high light tank my cardinals, rummynose, and cherry barb all come out but once the high lights kick on they take cover in the plants and don't come out much if at all until the low lights are the only ones back on. One thing that can often help this out a lot is the use of floating plants. If you have a lid you may have to lower the water level a little but frogbit and water sprite don't need much space as they are pretty flat. Small water lettuce works good in low light but need a bit more head room. You can also add an Indian Almond leaf or two as they release tannins which will darken the water and the added benefit that they release anti-bacterial and fungal properties as well. This type of water is very common for many types of tetras in the wild.

 

[Masha]

Thank you, Rivercats, that makes sense. I was wondering if floating plants might help. I've got space below the hood.

Also, the plan of dimming the light with something might help too.

By chance, my tank has quite a lot of tannins at the moment from the driftwood.

 

[Rivercats]

Floating plants tend to make skiddish fish feel more secure besides lower the light levels below them. They are a win/win!

 

[Masha]

Drat. There used to be tons of water lettuce in my pond but I got rid of it. Maybe my father still has some.

If so, how can I clean it? Dilute hidrogyn peroxide? Lots of critters in my father's pond!

 

[Rivercats]

Pond plants are the hardest ones to clean. I pour straight hydrogen peroxide over them and then let them float in an almost 1:1 ratio of peroxide to water. Problem with water lettuce and water hyacinths are they have such deep crevices at the leaf bases and right where the roots meet I've found it hard to get 100% of everything killed off of them.

 

[Masha]

Hmmm. Sounds like a bad idea then. I'll just have to see what I can find. Most of the shops around here have a bit of a limited plant selection.

 

[Masha]

Sorry for all my many posts-

Just occurred to me. When they are out and about, (in the dark, like now) they dont really seem nervous. I can go up to the tank, even wave my hand around and they just look at me, no panic hiding.

So it must be the light. I think I'll leave it off for a few days, until I've figured out a way to shelter them from it.

 

[Buu]

I'm buying some red root floaters from Peabody's paradise for exactly this reason!

 

[Masha]

I'm buying some red root floaters from Peabody's paradise for exactly this reason!

Jealous ! I doubt they ship to South Africa

 

[Buu]

Oh no! Didn't realize you were so far! I don't think he does either. I hope you can find a cool local there who does though! They look so pretty.

 

[Masha]

Oh no! Didn't realize you were so far! I don't think he does either. I hope you can find a cool local there who does though! They look so pretty.

Yes, you have no idea how jealous I get of all of you , all the amazing plants and fish you have access to. But actually, I searched the South African planted tank forum and found a specialized place about an hours drive away that looks really good. Am going there next Saturday. Can't wait! Might even get my new black widow tertras then.

In the meantime I'm keeping the lights off most of the time.

I noticed that my current black widows dont go pale when they hide, so I think they might not be very stressed. I know they go all silvery when they are scared.

 

[Fresh2o]

I had a similar situation but with a different type of tetra (Gold). I provided lots of hiding spaces in the form of large flat rocks and they took advantage of it. I really only saw them out at feeding time. If I removed the hiding spaces then they would hang out in a corner.

I read about dither fish being used to make the more timid species of cichlids relaxed and less reclusive. I then added 6 longfin blue danios (its a 20 gallon tank). Danios are always on the move and swim freely thorough out the tank and in no time the tetras emerged from their hiding spaces and joined them.

Not saying that you should add danios. If more skirts are in your plans, then IMO things should improve.

Btw I'm not home when the lights go on so I don't know if my fish "panic" initially. I usually have some ambient light in the room from an open shade so the change from dark to light may not be as extreme.

 

[Masha]

Thanks for that, Fresh2o. I'm hoping a larger group will help.

I did not know that about dither fish. I've still got to work out what other fish I can add to the tank, but smaller schooling fish are on my list.

I've got 4 silver tips at the moment, maybe I should get more of them.

 

[Masha]

Just a report-back in case anyone else ever has the same problem.

I've been keeping the light off most of the time, only switching it on when the room light is already very bright. Then gradually increasing the time the lights are on. Fish still hide, but not all the time and now they come out and swim around in the later afternoon / evenings even if the light is on, this seems to be their "busy" time.

I got some floating plants but not enough to really make a difference - am a bit limited by what is available.

I've now got a little school of baby black widow tetras in the quarantine tank. That has quite a bright light and they seem completely unworried by it. I'm a bit apprehensive over how my two adult black widows will react when I introduce six new babies into the tank!