Zebra Danio Turning Pale?

[mcfc4eva]

I have 4 Zebra danio's, (2 male, 2 female). They share a ~5 gallon tank with 1 female comet. Everytime I do a complete water change, the black stripes on the zebra fish fade significantly, so the fish almost look albino! However after 5 or 10 minutes they settle and the black/blue stripes re-appear. I thought this might be caused due to stress? However recently I purchased another tank for breeding purposes. I set this up and put the females in it, again they turned pale, I fed them and came back about 2 or 3 hours later - they was still really pale and eventually just stopped darting around and began either swimming slowly or just resting on the stones!

I don't know why they turned pale, so I decided to add one of the males to see if this would perk them up, came back about an hour and a half later and all three of them was pale and slow/non-movers!

I haven't got a filter for the breeding tank as I didn't think I'd need one if it was just a "temporary" one, is this the cause or is it some chemical reaction if the water is slightly different? The water was only 6 to 7 inches deep, plus half inch of pebbles - maybe that was the reason?

In the end I put them all back into the community tank where their stripes soon came back!

Can anyone tell me why they turn pale and how to stop it? If I left them in, would they just settle in a day or two?

Thanks,
Michael

 

[Tokis-Phoenix]

Hi and welcome to the forum .


Yes fading in danio's is a sure sign of stress- what is the temp of the water you are putting back in the tank and are you dechlorinating the fresh new water- what are the size of the water changes you are doing as well?
Do you have any accurate test kits for ammonia, nitrites, nitrates and ph? The danio's stress sounds very much like it is water quality related, so its important to test the water for these stats to see what their exact levels are etc.

Danio's are active shoaling fish and do best in groups of 7 or more, due to this and their high activity levels they do much better in tanks of 10gallons or more. The comet goldfish is sure to outgrow the 5gallon tank in less than a year, so you should consider getting it a larger tank or moving it to a pond etc (comet goldfish can grow to 15inches+ long).

How large is the breeding tank? If you want to breed danio's successfully, its vital to have suitable and established filtration in the tank- danio fry in particular are very sensitive to water quality and will not survive for long in a small tank that has still water.
How familiar are you with the concept of cycling tanks as well? To keep good water quality and so ensure fish are healthy and not stressed, its vital to learn about the nitrogen cycles process (in fishkeeping called "cycling") .

 

[mcfc4eva]

Yes fading in danio's is a sure sign of stress- what is the temp of the water you are putting back in the tank and are you dechlorinating the fresh new water- what are the size of the water changes you are doing as well?
Do you have any accurate test kits for ammonia, nitrites, nitrates and ph? The danio's stress sounds very much like it is water quality related, so its important to test the water for these stats to see what their exact levels are etc.

Danio's are active shoaling fish and do best in groups of 7 or more, due to this and their high activity levels they do much better in tanks of 10gallons or more. The comet goldfish is sure to outgrow the 5gallon tank in less than a year, so you should consider getting it a larger tank or moving it to a pond etc (comet goldfish can grow to 15inches+ long).

How large is the breeding tank? If you want to breed danio's successfully, its vital to have suitable and established filtration in the tank- danio fry in particular are very sensitive to water quality and will not survive for long in a small tank that has still water.
How familiar are you with the concept of cycling tanks as well? To keep good water quality and so ensure fish are healthy and not stressed, its vital to learn about the nitrogen cycles process (in fishkeeping called "cycling") .

What is the temp of the water... Well its room temprature, I don't have a heater in either tank so I'd say around 70-74F.

Are you dechlorinating the fresh new water... Yes

What are the size of the water changes... between 20 and 50% per week, depending if it is cloudy and then a 100% change once a month.

Do you have any accurate test kits... No, I thought comets and danios are amongst the easiest and fish to keep and very hardy/tolerant to different water - so I thought I needn't bother?

As for the comet, I will be getting a bigger tank eventually. I originally got the 25L one just to "look nice" and it was the only one I could afford, as it was a impulse purchase! When I have the money, I'll invest in a bigger tank, within the next year!

The breeding tank is a little smaller, at just 21L, I don't know the exact measurements but I'd say it is 22"L x 10"W x 15" D

When you say "cycling tanks" I would assume you just mean the quantity of water a filter can cycle in a certain amount of time, however you mentioned about the nitrogen levels so now I'm completely confused...

Is all the chemistry involved really that important for these hardy fish?

 

[Tokis-Phoenix]

Yep, water chemistry is important even when you are keeping hardy fish like comets and danio's- you can still accidentally kill such hardy fish if the water quality goes bad.

With the cycling tank thing. Basically fish pee and poop ammonia, and ammonia is toxic to all aquatic life. In a tank that isn't filtered, the ammonia will just build up and take a toll on the fishes health and eventually kill it- so its very important to filter the tank. The reason why its important to filter the tank is that a special nitrifying bacteria will establish itself on the filters sponges, and as this beneficial bacteria establishes itself in the filters sponges it will convert ammonia (very harmful to fish) into nitrites (harmful to fish but not as harmful as ammonia) into nitrates (not harmful to fish unless in very excessive levels). This is the nitrogen cycle .

If you want to have good water quality in your tank, its vital to have this beneficial nitrifying bacteria in your tanks, otherwise the water quality in the tank will remain unstable and toxins in the water will harm/stress the fish etc. The process of the bacteria establishing itself in the filters sponges is called cycling and it can take a while for the bacteria to fully establish itself (often at least a few months), but when it does (as long as you don't do anything to harm the bacteria) the water quality in the tank will always be good as long as you keep up with your once weekly water changes .

The bacteria will start to establish itself on its own in the tank as soon as you turn on the filter and add fish to the tank, but there are many things that you can do to accidentally kill off or harm the beneficial bacteria. Because your fish look pale every time you do a water change, here is a list of possible things that you could be doing wrong to kill of the beneficial bacteria and so cause the water quality to go bad and stress the fish;

1.While the bacteria gets rid of ammonia, it also needs a constant source of ammonia to survive (usually supplied by decomposing muck in the filters sponges that it has sucked in)- if you deny the bacteria its ammonia, it will starve and die off. Common actions which can cause this are;
a. Over-cleaning the filter. When it comes to cleaning the filter, you should only remove enough muck for it to run smoothly- never clean it so that its sparkling clean.
b. Doing water changes that are too large- doing 100% water changes will cause harm to the beneficial bacteria.

2. Cleaning the filter in un-dechlorinated water- the filter is where the beneficial bacteria primarily resides, and if you clean the filter in undechlorinated tap water the chlorine in the water will kill the bacteria off. When you clean the filter, you should ideally do it in water left over from water changes, as this water is the least likely to stress/harm the bacteria .

3. Not dechlorinating fresh tap water that goes into the tank will also kill off the beneficial bacteria.

(Having insufficient filtration for the bioload of the tank can also cause water quality to become unstable and bad, as obviously can not cleaning the tank regularly enough etc.) More info on cycling tanks and water quality etc;

http/www.fishforums.net/content/New-to-t...-tank-syndrome/


I would put my money on the fishes stresses being down to issues with the water quality, i noticed you said you sometimes do 100% water changes when the tanks water goes cloudy, doing such a massive water change could kill off the beneficial bacteria and cause the water quality go bad and make the fish stressed.
I would advise that you buy some accurate water quality testing kits from your local fish store and test the water for ammonia, nitrites, nitrates and ph to see what state the water quality is currently in (because even if the water looks clean, it still may have toxins like ammonia in it- the only way to know for sure is to test the water). If you tank is cycling then you will need to test the tanks water quality quite often to make sure that toxins like ammonia aren't building up in the tank, and also so that if they are you can do a small water change with dechlorinater to help remove them . In an established tank, ammonia and nitrites will always be 0, while nitrates should be between 1 and 40. If there is any sign of ammonia or nitrites (or a complete lack of nitrates for that matter), then it means that the beneficial bacteria is still establishing itself/the tank is cycling and that you need to keep a close eye on the water quality to help keep it good .

With the cloudy water issue, if the water goes a cloudy whitish/foggy color then it means that the tank is suffering from a bacteria bloom. These blooms are not uncommon in new tank set ups which are still establishing themselves, and will stop happening as the tank establishes itself more with age and good tank maintanence. Bacterial blooms usually aren't harmful to fish unless they are very intense, all you need to do to get your fish through them and help prevent them happening again is to simply do regular small water changes with dechlorinater and to increase the aeration in the tank .

 

[The-Wolf]

I have 4 Zebra danio's, (2 male, 2 female). They share a ~5 gallon tank with 1 female comet.

 

[mcfc4eva]

I traded my 5 Gallon tank in for a 15 Gallon tank. One of my females managed to find a gap in the lid (where the wires run through) which must have only been about 8cm x 2cm, and somehow jumped out on it's first night! It was an incredibly small gap, and I'm surprised she found it. Unfortunately I was in bed when it happened and found her today! At least she died in style, I'm quite impressed she managed that. Anyway, i've since blocked that hole with cotton wool so no more stunts. The fish are doing well and liking their new tank, and until I can afford another filter - they aren't going to be bred.

Thanks for the advice!
Mike

 

[Tokis-Phoenix]

Ah its a shame the danio jumped, but at least you've sorted out the tanks gap problem, most fish (particularly the smaller ones) have the ability to jump out of tanks so its important to always keep the tank properly covered . Good to hear you got a larger tank though (i assume you kept the old fish tanks filter and are running it in the new tank?). When the tank is more established it would be a good idea to get some more zebra danio's (you could also opt for leopard danio's, since they are the same fish as zebra danio's and are only a different pattern variety, so will shoal and interact with the zebra's fine ).