Help with new danios

It sounds like it might not be the squeaking, but stress from the water quality. Do you have test tube test kits yet? You want to check your ammonia and nitrite levels immediately to see where they are at, and if that's the stressor. If the levels are high, you will need to do immediate, large, and frequent water changes to get them under control.

Live plants help buffer nitrogen compounds. I'm doing a s l o w cycle with a bunch of little fish and a lot of live plants. I check the chemistry daily, and though my water looks like milk, there's no harmful nitrogen compounds.

You can expect your water to get very cloudy as the beneficial bacteria colonies establish themselves, and opportunistic bacteria fill the void in the water column while they grow.

Also, do you have any hiding spots for your danios? They'll feel much better if they have either live plants to hide under, or those cheesy little caves you can buy at any walmart, petsmart, etc., or your LFS will have them (please avoid walmart or petsmart as a personal request from me).

Are you using gravel as a substrate medium (bottom)? Do you have a filter? Does your filter have a biowheel, or are you using undergravel? Heater working? Water temperature? There's a lot to know, and after doing it all wrong for years, I started taking it pretty seriously for a couple of months using this site as a guide.

Your nitrogen levels are the ASAP action item though... Then probably worry about hiding spots. The aggression you're seeing is probably territory related. More territory, less aggression.

good post but I have one thing to add:

Zebra danios are generally quite nippy towards each other and even more to other fish.
Dont worry too much as they are hardy but keep that cycle going.

Do you have any plants? My guess is that the fish have figured out they're swimming in their own waste, which gets them sketchy, so you're just going to have to ride the storm and cycle the tank. In addition to ammonia, you should also be charting nitrites daily, and eventually nitrates. Ammonia will spike, drop off, and then nitrite will spike, and drop off, and then nitrates (the non-harmful compound) will accrue. Nitrates over time will be toxic, requiring water changes. Your tank will be cloudy through the whole process, which takes anywhere from 2- 3 weeks to 2 - 3 months. Then you're ready to go.

If you don't have one, I highly recommend a filter with a biowheel. Biowheels form an ideal surface for nitrifying bacteria to form, in addition to your tank and substrate. Since there's so much more oxygen available to them (18% in air rather than 2% in water), they grow very densely, and my guess (keyword: guess) is that your tank will cycle faster, and handle more "chemistry" with one than without. Regular water changes also stabilize the pH, carbonate hardness, and general hardness of the tank. Those terms don't matter much now; all you need to know is that regular water changes + cycled tank = happy, live fish.

On the bright side, zebra danios are tough little fish, and many people choose them because they are so hardy (I did). Your tank wasn't cycling or doing anything at all until you added those danios, and then the chemistry of life's magic started to kick in. Once your tank is cycled, it will regulate itself (with your occasional common sense, weekly water changes, and without overfeeding).

Sorry, also, did you rinse your gravel and all ornaments before adding them? That contributes to cloudinessl a good filter will remove that over time. RESIST the temptation to tamper with your water; don't add any chemicals except water conditioner for chlorine and chloramines.

Abilor said:

Sorry, also, did you rinse your gravel and all ornaments before adding them? That contributes to cloudinessl a good filter will remove that over time. RESIST the temptation to tamper with your water; don't add any chemicals except water conditioner for chlorine and chloramines.

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just curious: is it rinsing or not rinsing that contributes to cloudiness?

I wouldn't worry too much about the biowheel filter recommendation, as long as you have an adequately sized filter for your water capacity it'll work. Every bio filter system has its advantages and disadvantages but as long as you perform the appropriate maintenance they all do the same job.

sorry, NOT rinsing contributes to cloudiness.