Psychotic Danio's?

[avinalaff]

Hi,

I'm extremely new to keeping fish and have a bit of a problem. I have a 28 litre tank which had 2 cardinals, 3 plattys and 6 zebra danio's in it. After a few days we found one of the cardinals dead and half eaten, closely followed by the other one. Then the same happenned with 2 of the zebra danio's. We noticed that 2 of Zebra's were extremely agressive toward the other 2 zebra's (I'm afraid I can't tell you their gender). The plattys keep themselves to themselves but have now taken to staying in the top corner of the tank next to the filter.

The zebra's and plattys don't appear to be bothering with each other.

We were advised that all of these fish were non-aggressive and could therefore share space, and in fact that the zebra's would shoal but this isn't the case. The last thing I wanted to do was create a fishy bronx !

I've read some posts about aggressive fish and the tank has a plant in it and a couple of hidey holes but the aggressive zebra's are chasing their victims wherever they hide.

I would be grateful for any advice.

Phil

 

[SuperColey1]

Zebra Danios are very active fish, but never heard of them being aggressive.

They often look like they are chasing each other around but thats their nature.

Ideally they should be in groups of 6 or more to shoal.

I would guess that the other fish have died of other causes rather than being killed by the Danios.

If a fish dies then others will all join in the feast like vultures, as after al their instinct is to take in as much food as possible and also a freshly dead fish is something different to their usual diet and therefore a treat to them.

If I were you I would get the 2 remaining danios 4 mates (after finsing out what is killing your fish)

You will notice that they look like they are chasing each other but that is how they shoal.

A large group will chase each other but in the main stay together.

Hope this helps

andy

 

[Christine1014]

Danios are a very boisterious fish, and in my experience seem to love chasing each other around, but basically leave everyone else alone (and they chase, but don't catch). You say you're new to fish-keeping... how long have you had your tank set up? Did you cycle it, and if so, how? I'm thinking perhaps some of the fish died, and THEN the danios (or something else) came along and started picking at the carnage...

 

[avinalaff]

Many thanks Christine and Andy, excellent advice. We've had the tank for just over a month, the fish have been in there for about a week. We did cycle the tank, but weren't really sure what we were doing. I will test the water tomorrow to see if we can find the cause of the dying fish. Having read around a little more, a sign of nitrate poisoning appears to be when the fish group together just under the surface and this is what the platies are doing.

Now having observed the danios further, I can see they don't actually appear to be hurting each other so thanks again.

 

[Christine1014]

good luck! And feel free to come back and post your water stats tomorrow. Maybe we can give you a little more insight then. however, if it looks like any of your fish might be gasping for air, a nice big water change is most certainly in order.

 

[celaeno]

your problem is overstocking and/or bad water stats. ideally, zebra danios need at least a 20 gallon tank because of how active they are. platies need at least a 10 gallon, but the larger, the better.

the fact that the platies are huddling together is either due to the aggressive danios and/or poor water.

 

[SuperColey1]

I didn't read the original post properly and read it as 29G rather than 28Ltr.

Poster above is absolutely correct that because of the nature of racing around Danios do need to be in at least a 20G tank.

With a 28Ltr tank you are really limited as to what you can keep really.

The inch per gallon (you have approx 7-8G) rule has huge limitations in that it doesn't take into account that a fish maybe 1" when fuly adult and therefore this rule would say you could keep 8, but fish like Neons and Danios really need room to swim end to end as wel as they swim so quickly.

Sorry if this isn't what you want to hear, but IMO the best size to start with is something like a 30 inch or 36 inch tank as this allows room for mistakes.

We've all made this mistake as fish shops often give incorrect advice after all, they are in the business of selling.

A decent all in 29G would set you back around £30-£60 on ebay although you would most probably have to collect. But you would most likely get all the kit you need and then you could have a few more fish, without as many problems and use your 28Ltr as a fry tank or quarantine tank.

Good luck

Andy

 

[Christine1014]

I opened this thread again this morning and the first thing that caught my eye was the 28L... I must have been sleepy last night, because I also thought I read "gallon!" I think in that sized tank you could keep the platties OR the cardinals... but both would be pushing it.

 

[The-Wolf]

28 litres is way way too small for zebra danios, even dwarf danios would create merry hell in that sized tank.
the solution is rehome the danios to a larger tank. do it before you end up with one danio that has killed everything else.
trust me it will happen.

 

[avinalaff]

First I should say that I got it wrong about the size of the tank in the first place, I edited the post and signature once I found the correct information, so not your mistake but mine.

Second, many thanks for all the great advice. I now need to find a home for the danios or consider upgrading to a larger tank. Thanks again for all the fast responses, there's a lot more to this that I'd first imagined but it's slowly becoming clear!

 

[mark.w.jones]

First I should say that I got it wrong about the size of the tank in the first place, I edited the post and signature once I found the correct information, so not your mistake but mine.

Second, many thanks for all the great advice. I now need to find a home for the danios or consider upgrading to a larger tank. Thanks again for all the fast responses, there's a lot more to this that I'd first imagined but it's slowly becoming clear!

I wouldn't necessarily get rid of the tank though. It'd make a great tank for a single Betta but is really no use for a community tank. 20 US gallons is really a good size to go for with a beginner tank as it allows for a fairly wide range of stocking options. Strangely, the bigger the tank the easier it is to maintain and keep stable.

 

[SuperColey1]

I wouldn't suggest Tetras for a small tank. they like to be in groups and shoal and when they shoal they like to swim fast sometimes, therefore the same prob as the danios.

I agree, would make a lovely tank for a Betta. Too many 10L cups for Bettas so 28L would be very nice.

Andy