Danios at surface

[Jaynewfishfan]

Hello. My danios are all swimming at the surface of the tank - this is new behaviour and I’m worried for their health!

The 145 litre aquarium is 6 weeks old, we had only 10x danios (5x zebra and 5x pearl) during that period.

The water was tested at the water garden centre (where we bought the fish) and deemed good enough to introduce our other fish from an older, much smaller tank.

I introduced 5x cardinals, 1x sucker, 2x small frogs and 1x snail, all seemed good for 2 days.

I had the water retested, which showed I needed to add Denitrol to assist the bacteria growth, otherwise the water condition was perfect.

BUT

As soon as I added the Denitrol (2 hours after adding Biotopol, as directed) the danios ALL started to swim at the surface, and have not left it since. I have also noticed a slight greasy film on the surface of the water.

Post-Google/Wikipedia searching, I have introduced an aerator to break the surface tension, in case there is an oxygen shortage. But the other fish are all at the bottom where they have always been, without problem.

Does anyone have any idea what could be wrong, either regarding the fish swimming at the surface or the cause of the greasy film?
Really appreciate your help, thanks.

 

[Brookster123]

Look up cycling an aquarium

 

[Jaynewfishfan]

Look up cycling an aquarium

Brookster, thanks.
Just checked on swelluk.com, think I’ve followed most of their advice already. I haven’t done a water change yet though so will try that.

I’ve had the danios in there as “hardy fish...(that) tolerate low levels of ammonia and nitrite”, but now feel bad that perhaps “no fish should be exposed to any levels of ammonia or nitrite at any time as it compromises their welfare.“

But do you think their swimming at the surface was due to a lack of oxygen? Interestingly (and hearteningly) they have now moved back to their more natural place a bit lower down, away from the surface. And the film has gone. Maybe the aerator bubbles did the trick?

Also think I’ll buy a testing kit of my own, rather than having to go to the water garden centre.

Thanks for your advice

 

[Brookster123]

A water change will help. What are you using for water conditioner?

 

[Aiken Drum]

Do a water changes sufficient to keep ammonia + nitrite combined below 0.5ppm. If it goes above 0.5ppm do 25% water change, if it gets to 1.0ppm do either 50% change or a couple of 25% changes a few hours apart. Check daily and do water changes as needed until your cycle has established and your ammonia and nitrite stay at 0ppm on their own. Until you can test your own water and keep a daily check on your parameters, i would be doing 25% changes daily. API master test kit is a good test kit that covers what you need to cycle a tank.

Danios staying at the top isnt unusual, mine mostly stay in the top 1/3 of the tank except when they are chasing food. A few literally stick to the surface.

 

[Jaynewfishfan]

A water change will help. What are you using for water conditioner?

JBL Biotopol
(www.JBL.de)

It has been working well until now. The JBL Denitrol aquarium starter recommends putting biotopol in before adding the aquarium starter

 

[Jaynewfishfan]

Do a water changes sufficient to keep ammonia + nitrite combined below 0.5ppm. If it goes above 0.5ppm do 25% water change, if it gets to 1.0ppm do either 50% change or a couple of 25% changes a few hours apart. Check daily and do water changes as needed until your cycle has established and your ammonia and nitrite stay at 0ppm on their own. Until you can test your own water and keep a daily check on your parameters, i would be doing 25% changes daily. API master test kit is a good test kit that covers what you need to cycle a tank.

Danios staying at the top isnt unusual, mine mostly stay in the top 1/3 of the tank except when they are chasing food. A few literally stick to the surface.

That’s great, thanks, I’ll start doing the water changes - I haven’t done any yet because I thought I had to leave everything alone - filter, water etc. - until it is properly established.

Good news that it’s not unusual for them to be ‘sticking’ to the top, it was the fact that they hadn’t done it until now, i.e. a behaviour change after I altered the water condition, that worried me.

Thanks fully they seem to be whizzing around all over the place now, like they used to...

Funny how much one emotionally invests in these little creatures

 

[Aiken Drum]

That’s great, thanks, I’ll start doing the water changes - I haven’t done any yet because I thought I had to leave everything alone - filter, water etc. - until it is properly established.

Good news that it’s not unusual for them to be ‘sticking’ to the top, it was the fact that they hadn’t done it until now, i.e. a behaviour change after I altered the water condition, that worried me.

Thanks fully they seem to be whizzing around all over the place now, like they used to...

Funny how much one emotionally invests in these little creatures

The beneficial bacteria doesnt live in the water, it lives on the surfaces of your filter media, substrate, decorations etc. Doing water changes will have very little, if any, impact on your bacteria. The exception to this would be bottled bacteria like your JBL Denitrol. Not a brand ive ever heard of. It looks German? As this has been introduced into the water it will need to establish on the above mentioned surfaces. I would give the product 24 hours to establish before a water change, and you may want to top it up after a water change.

Note these bottled bacteria products arent the magic bullet they claim to be. At best they will speed up your cycle from months to weeks, at worst they do nothing. It doesnt take very much to kill off all the beneficial in the bottle before it even gets to you. You have no idea how it might have been stored or transported. Water changes and patience are key, bottled bacteria is just something that may help.

 

[Jaynewfishfan]

Again, thanks very much for the thoughtful advice. Great that even on Christmas Day there are so many people willing to chip in on how to make life better for the fish in my aquarium!

Ok, I’ll give it a day or so for the Denitrol to settle, then head back to the garden centre to get a water sample tested. At that point I’ll also get a testing kit.

The garden centre are very good, will not supply fish unless water is in a correct state and are always willing to give free advice - I trust them. The Denitrol website is German but I bought it from the garden centre.

Thanks

 

[Aiken Drum]

Dont trust what a pet (or garden) store tells you. Do your own tests, learn to understand what the tests mean.

Let me take a guess. Maidenhead Aquatics?

 

[Jaynewfishfan]

Will do.

Kenchester Water Gardens.