5 Zebra Danios with Reddish gills and and some red spots



I have a 5 gallon tank with 5 zebra danios in it. I have had the fish in it for a little over 2 weeks. I got the water tested before I put the fish. I have the EheI'm pickup45 filter. I have been doing water changes at least once a week and I just recently cleaned the filter sponge.

I noticed even just a few days in the long fin ones have reddish gills. I have 3 long fin and 2 short fins. Up to now two weeks later it hasn't gone away. From my observation, they are all behaving normally and eating well. I have sand at the bottom of my tank if that means something.

I went to the fish shop I bought them at and they said that it is too much ammonia. They told me to do 50% water changes every two days and come back next week to test again. I would just like to get others opinions about it.

I also have been using water conditioner every time I do water changes.

Here is a video with them. I don't know how clearly you can see anything.

  • Moderator


Welcome to FishLore!

I'm sorry to have to tell you that you have two major problems. The first is that your tank is way too small for zebra danio's. They should be in nothing smaller than a 20 gallon (long).

The second problem is that they are suffering from ammonia poisoning due to being in an uncycled tank. I highly recommend you read up on the nitrogen cycle (words will be link to article), since it is the most important thing to understand when keeping fish.

Sadly, to correct the situation, you will either need to get a larger tank. or return/rehome your zebra danio's and get a betta for the 5 gallon tank.

I'm sure this isn't what you wanted to hear (I know it wasn't what I wanted to hear when I got off to a bad start) but unfortunately contrary to what you would expect. more often than not the advice you get from the "experts" at the fish store is incomplete or outright wrong.

But feel free to ask any additional questions you may have. Believe me, this forum is full of people eager to help you be a successful fish keeper.

Best of luck!


I agree with jdhef, it sounds like ammonia poisoning. The tank is to small for that bio load, and even if your filter bacteria does catch up, you will be walking a fine line to disaster. A 5 gallon tank is really only good for a Betta or shrimp tank. I would recommend either upgrading to a 20 gallon long or bigger if you really want to keep your fish that you have, or re-homed them and get a Betta and a couple of snails.

As for right now, I would recommend 2 purchases. The API Master Test Kit so you do not have to keep running to the pet shop to test your water. Plus most pet places uses strips which can be highly inaccurate. They also just say things like "Your water is just fine" with out giving you the results. Plus you should test your tap water as well. You could have Ammonia in that, which can be compounding your problem. The second purchase would be SeaChem Prime. It is basically an all in one water conditioner that also helps with ammonia and nitrite. It makes ammonia and nitrite less toxic up to 1ppm which will help your ammonia poisoning in the tank, and if your tap has ammonia as well, it will lessen that problem.

As for water changes, I would do 50% daily to keep the ammonia down a bit. I would also recommend you vacuum your substrate daily as well, because that could be contributing to your problem.

Hope I've helped.
  • Thread Starter


Thank you both for the help. If I were to do the water changes, should I just mix up the sand first and then do the water change? I currently have no vacuum. I am actually using water ager cn right now when I do water changes.

My plan is to upgrade my tank around October as I just got everything set up with this tank and I will be moving to a bigger apartment in October. Would I be able to make do for a few months?


No, don't stir up the sand. You can get an aquarium syphon vacuum pretty cheap, and just swirl it just above the sand to dislodge anything on top. That way nothing floats off and settles somewhere else.

You can make it to October if you stay up on your vacuuming and testing. You'll more then likely have to do water changes every day, to every other day depending on your test results and no over feeding happens. You could also do spot cleaning using a turkey baster to get left over food and stuff off the bottom.

You have to keep the water as clean as possible until then.


Welcome to the forum!

If you didn't already, I would also suggest picking up Stability, TSS, or some other form of beneficial bacteria to help the cycle along more quickly. I personally prefer Stability because it still allows you to perform tank maintenance, unless TSS, which you basically put in and then can't do anything like water changes for 2 weeks.

I can't see in the video, but from what you described, I agree with others on here and the store, too much ammonia. My understanding with ammonia poisoning (and someone please correct me if I'm incorrect) is that even after the issue is resolved, the redness may remain.

Also, I agree that they should be ok until October with the smaller tank for a few months. It looks like there is a good current flow too, which will help out with their time in the smaller tank. Danio are very hyper, so typically a minimum of about 24 inches in length is recommended for them, thus the minimum of the 20 long.

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