Glofish Danios staying at the top of tank

[Zero-]

Hi! I am brand new to the fish keeping hobby, I just got my first 5 fish two days ago, Glofish Danios, and I want to do the very best I can for them so they can have good lives.

I'm noticing that 4 out of 5 of my fish are staying at the top of the tank, right at the water line. They just swim around in a small circle around each other, underneath where the tank light is. One of those four stays a bit lower than the rest, but still pretty near the top, right under the light, though it occasionally goes to the middle, too, for a few seconds. I'm thinking the light is the issue, but I researched a bit and saw that fish need 12 hours of light and 12 hours of darkness, so I'm not sure. It's a bright, white light; I'm thinking of investing in a blue light, as well. The one that swims around the middle and bottom of the tank has been eating, but the rest don't. I've been giving them pellet food and flake food to try and find out what they prefer, but only one is eating, so I don't know yet.

I have a 10-gallon tank and it's filled almost full, up to the black strip that most tanks have around the rim. I also have a decent waterfall filter, an air pump with an air stone in one corner of the tank, as well as a heater and the water temperature stays between 76 and 78 degrees. I'm also worried that the air pump is blowing the food around too fast for them to eat and the filter is sucking it up too fast, so I tried turning the oxygen off for a few minutes while feeding them, but it didn't seem to change much. I don't really know what to think. If anymore info is needed, please don't hesitate to ask. Thanks in advance for any advice you can give me!

 

[Aiken Drum]

Fish staying at the surface is usually a sign they are struggling for oxygen. Either there isnt enough oxygen in the water due to lack of surface agitation and gas exchange or ammonia causing issues with the fishes gills preventing them getting oxygen from the water.

Do your fish appear to be gulping for air?

Having said that glofish danios are GM zebra danios, and zebra danios do tend to stay towards the top of the tank at the surface.

What do you know about the nitrogen cycle?

Did you cycle the tank before adding fish (fishless cycle)? If so how did you do this?

Or are you cycling the tank with fish in? If so how are you doing this?

Or do you know nothing about cycling a tank?

Do you know your water parameters? If so what are they? Actual numbers, not "my water is fine".

Have you done any water changes since getting the fish? If so, how much? When did you do this? Did your fishes behaviour change after the water change?

First course of action should be to change 50% of the water. If you dont know your water parameters do this every day until you can test your water.

 

[Zero-]

They don't look to be gulping for air, they're just sort of listlessly floating near the surface in the same spot. When the oxygen and filter waterfall drift them away from that spot, they slowly swim back and they keep going like that. Three of them are swimming now and only two are at the top.

I know a little about the nitrogen cycle, I just learned about it a few minutes ago. I didn't cycle the tank before I got the fish, though. I though the lady at Petco meant letting the tank run for 24 hours when she said "cycling the tank". She didn't explain that at all. But, I started the fish-in cycle process with a 50% water change maybe 3 hours ago, as suggested to me on another forum. Their behavior didn't change, though, not until I turned the light off for the night. One of the four fish that was floating with the rest at the top came down and is swimming now, another one started swimming around a few hours before the change, chasing the one that's been swimming around fine since I got them and being chased by him. I'm waiting for the water testing kit I just ordered to come in the mail soon, until then I can't test my water levels just yet.

 

[Aiken Drum]

The nitrogen cycle is the natural processes that go on in your tank that convert ammonia into less harmful substances.

Ammonia gets into your tank through various pathways. Fish waste, decaying uneaten food, and dead, decaying plants are common ammonia sources in an aquarium. Its also possible your tap water is an ammonia source. Chloramine is a common water treatment and when treated with most water conditioners the bond in the chloramine breaks and releases ammonia into the water.

Ammonia can be toxic to fish, depending on how much there is, and what the pH and temperature of your tank water is.

The first stage of the nitrogen cycle is the removal of ammonia. If you have real plants in your tank some of this ammonia will be absorbed as part of their natural growth. Generally though ammonia is consumed by denitrifying bacteria that lives mostly on your filter media. These bacteria consume the ammonia and produce nitrite. Unfortunately nitrite is pretty much as toxic to fish as ammonia.

The second stage of the nitrogen cycle is the removal of nitrite. A different denitrifying bacteria will consume the nitrite and produce nitrate. Nitrate is much less harmful than ammonia and nitrite, and for most aquariums the nitrogen cycle ends there. Excess nitrate is removed through your regular water changes.

A further stage of the nitrogen cycle can also happen, but its difficult to remove all the nitrate from a typical freshwater aquarium. Plants will absorb some nitrate in a similar manner to how it absorbs ammonia to grow. There are also nitrifying bacteria that consumes nitrate and gives off nitrogen gas which will simply offgas from your aquarium. This nitrifying bacteria is difficult to grow in freshwater aquarium.

“Cycling” a tank is the process you go through to grow denitrifying bacteria in your aquarium to consume ammonia and nitrite. You are said to be “cycled” when you have enough bacteria to consume all the ammonia and nitrite that your tank produces and turns all of it into nitrate. If you test the water of a cycled tank you should see 0 ammonia and nitrite and some nitrate.

 

[Aiken Drum]

To cycle a tank you need to grow denitrifying bacteria to consume ammonia and nitrite that your tank produces. The bacteria needs an ammonia source to grow colonies sufficient in size to consume all the ammonia and resultant nitrite and turn it into nitrate which typically you remove through your regular water changes.

A fish in cycle uses fish waste as an ammonia source and regular water changes are undertaken to ensure that water parameters are maintained at relatively non toxic levels.

Set up your tank. Make sure everything is running smoothly. Make sure you have used a water conditioner product with any tap water you have put in your tank. Seachem Prime is a water conditioner that will also detoxify some ammonia for a day or two, so is a good choice for a water conditioner while cycling a tank with fish.

You should have a test kit. Preferably a liquid test kit. It should test for ammonia, nitrite, and nitrate.

In ideal circumstances you should be starting a fishless cycle with a low bioload (number of fish). 1 small fish per 10 gallons/40 litres is a good number of fish, but this can be tweaked a little for fish that are social and don’t do well on their own. Ideally a hardy type of fish. You may have fully stocked (or overstocked) your tank before you knew about cycling. In these circumstances, if its not possible to return fish, you will have to make the best of it.

If you haven’t already done so, add your fish. Acclimate them to the water in your tank before doing so.

Feed lightly to start with. Daily as much as is eaten in 2 minutes, or as much as is eaten in 3 minutes every 2 days. You can increase to full feedings if you are confident your parameters aren’t getting too elevated too quickly and water changes don’t become a daily thing.

Start to regularly test the water for ammonia and nitrite. At least daily. Depending on your bioload you could start to see ammonia quite quickly. Nitrite will likely take a little longer to appear.

Your target should be to keep ammonia + nitrite combined no higher than 0.5ppm by changing water whenever your water parameters exceed this target. 0.5ppm combined is a level of waste that is sufficient for your cycle to establish but relatively safe for your fish.

If you see 0.5ppm ammonia and 0.0ppm nitrite (0.5ppm combined) then leave things be. If you see 0.5ppm ammonia and 0.25ppm nitrite (0.75ppm combined) then change 1/3 of the water. If you see 0.25ppm ammonia and 0.75ppm nitrite (1.0ppm combined) then change 1/2 the water. If water parameters get worse than these levels it may require multiple daily 50% water changes to maintain safe water conditions. This is more likely to happen with a fully stocked tank.

Remember to add water conditioner whenever you put tap water in the tank.

Over time the frequency of water changes and amount you need to change to maintain your ammonia + nitrite combined target will reduce. You can also start testing for nitrate and should see this rising. If you are finding the ammonia and nitrite in your tests are consistently low, and you aren’t already fully stocked, you can add a few more fish. It may take a few weeks to get to this point.

Once you add a few more fish, continue to regularly test the water and continue to change water if you exceed the 0.5ppm combined ammonia + nitrite target. With added bioload the frequency of water changes and amount you need to change may increase again until your cycle has caught up. Again once you are consistently seeing low ammonia and nitrite you can add some more fish. Rinse and repeat with testing, water changes, and adding fish when safe to do so until you are fully stocked.

You can then cut back on water changes to control nitrate only. Typically you want to keep nitrate no higher than 40ppm, but I would recommend changing some water every 2 weeks even if your water test says you don’t need to.

A fish in cycle from an empty tank to fully stocked can take several months.

A good way to speed up this process would be to put a small amount of filter media from an established filter into your filter, or get a sponge from an established filter and squeeze it into your tank water. Perhaps you have a friend who keeps fish who could let you have some? This will seed your filter with the bacteria you are trying to grow and speed up the process.

Another option is bottled bacteria like Dr Tims One + Only or Tetra Safestart. These products wont instantly cycle a tank as they claim but in a similar manner to adding established filter media they can seed your filter with the bacteria you are trying to grow to establish your cycle. These products are hit and miss as to whether they work at all, but are an option if established filter media isnt obtainable and may speed up the process from several months to several weeks.

 

[ColdKoi]

Danios do tend to hang out in the upper end of the tank, but like Aiken said, this sounds more like a water quality issue

Unfortunately most pet stores don’t take the time to fully inform customers on how to cycle a tank, or even tell people that it needs to be done. They just take the sale and move on to the next customer!

Until you get your test kit and are able to test the water, I would suggest you keep doing small daily water changes.

Fish can do weird things when there’s a change in environment too, this behaviour could be temporary while they get settled into the tank.

 

[Zero-]

To cycle a tank you need to grow denitrifying bacteria to consume ammonia and nitrite that your tank produces. The bacteria needs an ammonia source to grow colonies sufficient in size to consume all the ammonia and resultant nitrite and turn it into nitrate which typically you remove through your regular water changes.

A fish in cycle uses fish waste as an ammonia source and regular water changes are undertaken to ensure that water parameters are maintained at relatively non toxic levels.

Set up your tank. Make sure everything is running smoothly. Make sure you have used a water conditioner product with any tap water you have put in your tank. Seachem Prime is a water conditioner that will also detoxify some ammonia for a day or two, so is a good choice for a water conditioner while cycling a tank with fish.

You should have a test kit. Preferably a liquid test kit. It should test for ammonia, nitrite, and nitrate.

In ideal circumstances you should be starting a fishless cycle with a low bioload (number of fish). 1 small fish per 10 gallons/40 litres is a good number of fish, but this can be tweaked a little for fish that are social and don’t do well on their own. Ideally a hardy type of fish. You may have fully stocked (or overstocked) your tank before you knew about cycling. In these circumstances, if its not possible to return fish, you will have to make the best of it.

If you haven’t already done so, add your fish. Acclimate them to the water in your tank before doing so.

Feed lightly to start with. Daily as much as is eaten in 2 minutes, or as much as is eaten in 3 minutes every 2 days. You can increase to full feedings if you are confident your parameters aren’t getting too elevated too quickly and water changes don’t become a daily thing.

Start to regularly test the water for ammonia and nitrite. At least daily. Depending on your bioload you could start to see ammonia quite quickly. Nitrite will likely take a little longer to appear.

Your target should be to keep ammonia + nitrite combined no higher than 0.5ppm by changing water whenever your water parameters exceed this target. 0.5ppm combined is a level of waste that is sufficient for your cycle to establish but relatively safe for your fish.

If you see 0.5ppm ammonia and 0.0ppm nitrite (0.5ppm combined) then leave things be. If you see 0.5ppm ammonia and 0.25ppm nitrite (0.75ppm combined) then change 1/3 of the water. If you see 0.25ppm ammonia and 0.75ppm nitrite (1.0ppm combined) then change 1/2 the water. If water parameters get worse than these levels it may require multiple daily 50% water changes to maintain safe water conditions. This is more likely to happen with a fully stocked tank.

Remember to add water conditioner whenever you put tap water in the tank.

Over time the frequency of water changes and amount you need to change to maintain your ammonia + nitrite combined target will reduce. You can also start testing for nitrate and should see this rising. If you are finding the ammonia and nitrite in your tests are consistently low, and you aren’t already fully stocked, you can add a few more fish. It may take a few weeks to get to this point.

Once you add a few more fish, continue to regularly test the water and continue to change water if you exceed the 0.5ppm combined ammonia + nitrite target. With added bioload the frequency of water changes and amount you need to change may increase again until your cycle has caught up. Again once you are consistently seeing low ammonia and nitrite you can add some more fish. Rinse and repeat with testing, water changes, and adding fish when safe to do so until you are fully stocked.

You can then cut back on water changes to control nitrate only. Typically you want to keep nitrate no higher than 40ppm, but I would recommend changing some water every 2 weeks even if your water test says you don’t need to.

A fish in cycle from an empty tank to fully stocked can take several months.

A good way to speed up this process would be to put a small amount of filter media from an established filter into your filter, or get a sponge from an established filter and squeeze it into your tank water. Perhaps you have a friend who keeps fish who could let you have some? This will seed your filter with the bacteria you are trying to grow and speed up the process.

Another option is bottled bacteria like Dr Tims One + Only or Tetra Safestart. These products wont instantly cycle a tank as they claim but in a similar manner to adding established filter media they can seed your filter with the bacteria you are trying to grow to establish your cycle. These products are hit and miss as to whether they work at all, but are an option if established filter media isnt obtainable and may speed up the process from several months to several weeks.

Thank you for all of the info, it's a big help !

Danios do tend to hang out in the upper end of the tank, but like Aiken said, this sounds more like a water quality issue

Unfortunately most pet stores don’t take the time to fully inform customers on how to cycle a tank, or even tell people that it needs to be done. They just take the sale and move on to the next customer!

Until you get your test kit and are able to test the water, I would suggest you keep doing small daily water changes.

Fish can do weird things when there’s a change in environment too, this behaviour could be temporary while they get settled into the tank.

I think it definitely was just a settling in and water quality issue, for the most part. Most of my fish have come down and now they swim around and look to be having fun chasing each other, though they seem to stay up there together at night, probably just a nature thing. I only have one fish that seems to spend most of the day up there, I only see him/her (can't tell which yet) swimming around for a short window then they're back up there. Still waiting on my test kit to come in, but once I get it, I'm hoping I'll be able to make them happier. I'm also thinking of moving them to a 20 or 30 gallon tank so that they have more swimming space and I can start a community tank, as well as adding to their numbers. I've heard that Danios can become bored and irritable in 10 gallon tanks and small schools like mine.

 

[gilpi]

Water temp?

 

[Aiken Drum]

Water temp?

Says 76 to 78f. Too warm for danios maybe? Loss of O2 because of higher temp?