Danios Problem

ProjectMayhem · Jul 25, 2011

I'm having a problem with my danios, I had two in my tank which were fine and happy and I've had them for a while so they're quite big. Over the weekend I introduced two new ones which, being new are a lot smaller.

They were fine on Friday, Saturday and Sunday until this morning. The largest one of the originals (about 2.9 inches) is now swimming along the bottom on its own and chasing the other 3 if they come near him, which is very odd behavior for him and not the sort of aggressive behavior I have seen from these fish before. I'll provide details below but I suspect it may be the tank size.

Tank - 16.5 Litres (It's very hi-tech and can easily support these fish if not more) My thoughts here are room to swim, although they're small there might not be enough space for them. There is 1 pink plant just from one corner which they swim in and around, some wood on the other side which acts as a big arch which they swim through and 2 very small ornaments.

Water PH - 7.2
Nitrate and Nitrites are both 0
Ammonia is 0
Food - Fed bloodworm on Saturday and only fed that once that day, every other day fed twice goldfish flake an amount until consumed within 2 minutes.
Light - No lighting on this tank just use the natural light and bedroom light, no direct sunlight can reach the tank.
Temperature - 22 degrees celcius
Fish Sizes - The now aggressive one 2.9 inches, the next one down 2.0 inches, first new one 1.1 inches, the last 0.9 inches.
Water Changes - Weekly 50% changes on a Saturday.

I am currently having a Roma Fluvel 125 custom built for me which the fish will be moving into, it is due to arrive on Saturday (30th) then will be set up and cycled and they should be able to move in 10 - 14 days after this if I do everything correct, although if it's not ready after 14 days it's not ready and I won't be putting them in until it is.

Is there any reason for this aggressive behavior other than it might be because there isn't as much swim room as there was before??

micko · Jul 25, 2011

Room would be the issue. Its been said on here Danios need a tank of 3.5ft, 16.5 ltrs is seriously small.

ProjectMayhem · Jul 25, 2011

micko said:
Room would be the issue. Its been said on here Danios need a tank of 3.5ft, 16.5 ltrs is seriously small.

Well the room situation is about to be resolved but it has to wait until the tank is here, set up and cycled before I can do anything. They were all fine before and this has only just become a problem

micko · Jul 25, 2011

But you bought more fish a wee while ago knowing the tank was too small in the first place. Or have I got it wrong?

ProjectMayhem · Jul 25, 2011

micko said:
But you bought more fish a wee while ago knowing the tank was too small in the first place. Or have I got it wrong?

Well, I believed since the first 2 didnt have a problem and this isnt your ordinary 16.5 litre it should be ok, it's just the 2nd largest was becomming unsocial and seperate from the other just swimming on the bottom and I was told it was because there were only two of them, which is why I increased the number of them. Ideally when the new tank is set up and ready I will have 6 in total.

ZoddyZod · Jul 25, 2011

Danios constantly chase and 'harrass' each other and set up a social heirarchy. What you are seeing is the dominant fish stake his claim as the 'top dog'.

When I had only danios in a 3 foot tank. 1 fish staked out a small area on the gravel and would not tolerate any of the others in his 'space'.

Having them in a 16L tank is only magnifying the issue.

ProjectMayhem · Jul 25, 2011

ZoddyZod said:
Danios constantly chase and 'harrass' each other and set up a social heirarchy. What you are seeing is the dominant fish stake his claim as the 'top dog'.

When I had only danios in a 3 foot tank. 1 fish staked out a small area on the gravel and would not tolerate any of the others in his 'space'.

Having them in a 16L tank is only magnifying the issue.

It's not actually any staked out area, if he swims any where in the tank and they happen to swim where he's swimming he also gives chase, this hasn't been an issue before and now he's not doing it at all, maybe he's just grouchy on a morning lol

soybean · Jul 25, 2011

"this isnt your ordinary 16.5 litre"

Sorry, could you explain this? I'm looking at my betta's 17l tank and wondering what on earth you can mean.

Well anyway, you've bought them now, but could you put them in a larger container before your bigger tank arrives? Eg under-bed storage type box. Just move the filter into it?

ProjectMayhem · Jul 25, 2011

I'm watching them on webcam from work PC, he's not doing it at all maybe it was a one off.

The tank has an oxygenus attached which does what the name says and keeps the oxygen level constant meaning the tank can be slightly overstocked because the oxygen level will be kept at adequate levels.

ZoddyZod · Jul 25, 2011

ProjectMayhem said:
I'm watching them on webcam from work PC, he's not doing it at all maybe it was a one off.

The tank has an oxygenus attached which does what the name says and keeps the oxygen level constant meaning the tank can be slightly overstocked because the oxygen level will be kept at adequate levels.

the issue with a 16.5L tank and danios is not the amount of oxygen required, it's simply the amout of space. As you have seen already they are incredibly active and need sufficient space to zip around all day long.

soybean · Jul 25, 2011

ProjectMayhem said:
The tank has an oxygenus attached which does what the name says and keeps the oxygen level constant meaning the tank can be slightly overstocked because the oxygen level will be kept at adequate levels.

Perhaps if it was stocked with species suitable for the tank size, like the tiniest microrasboras or similar, but not danios. When you get them in the bigger tank you'll see just what they've been missing out on in that tiny space. You'll never catch them again!

So no chance of putting them in a temporary container in the mean time?

ProjectMayhem · Jul 25, 2011

soybean said:
ProjectMayhem said:

The tank has an oxygenus attached which does what the name says and keeps the oxygen level constant meaning the tank can be slightly overstocked because the oxygen level will be kept at adequate levels.

Click to expand...

Perhaps if it was stocked with species suitable for the tank size, like the tiniest microrasboras or similar, but not danios. When you get them in the bigger tank you'll see just what they've been missing out on in that tiny space. You'll never catch them again!

So no chance of putting them in a temporary container in the mean time?

No, they were in a 120l tank mentioned in a previous post in the emergancies however after exhausting all explanations as to why the fish were dying have decided it was the 2nd hand tank itself as a chuck of glass was filed down and a section sealed to the hole, I decided the silicon must not have been fish friendly as there was nothing wrong with it, thats why they're in a 16.5, I even have the tank full to the brim so it's the whole 16.5.

I wouldn't have put Danios in this small tank if I had my way but in just over 2 weeks they will be enjoying a lot of room and some more friends.

soybean · Jul 25, 2011

Having not read your previous post I presumed this was your usual setup. It does read like that.

Anyway, hooray for new tank on the way, and any weird behaviour is them sorting out a pecking order. All is well.

ProjectMayhem · Jul 25, 2011

soybean said:
Having not read your previous post I presumed this was your usual setup. It does read like that.

Anyway, hooray for new tank on the way, and any weird behaviour is them sorting out a pecking order. All is well.

I know most people won't remember it but wasn't sure if it was relevant if people thought I was a fish battery farmer lol