Feeling disheartened and sad after adding cardinals to my tank!

[Fisharefriendsnotfoody]

So tank has been going well. Started with 4 zebra danios, then added 2 leapord danios to make a group of 6.

They've been happy for weeks so thought would add a group of 6 cardinal tetras yesterday.

Well its been a disaster. The danios repeatedly chasing the cardinals and then have ended up ripping off fins and killing two in the night.
I am so upset by this. Really disheartened that I thought these could live harmoniously together as most things I've read said they are both good community tank mates!

Feeling so Sorry for those two poor little fish and just really hope the other four make it now.

Whats the deal with my danios?
Tank is a 53l. No ammonia or nitrites.

 

[DoubleDutch]

Seriously doubting the danios killed the cardinals. The fish are not quite tempcompatible btw (danios cool water / cardinals.warmer)

Most fast dieing cardinals die by Ph-shock (difference LFS and buyer's water)

 

[Fisharefriendsnotfoody]

Seriously doubting the danios killed the cardinals. The fish are not quite tempcompatible btw (danios cool water / cardinals.warmer)

Most fast dieing cardinals die by Ph-shock (difference LFS and buyer's water)

I watched them have their fins torn off....

Or are you saying they were already dying and the danios took advantage of this?

 

[Fisharefriendsnotfoody]

Tank is at 25 degrees which I thought suitable for both

 

[DoubleDutch]

I watched them have their fins torn off....

Or are you saying they were already dying and the danios took advantage of this?

I think that is more.plausible.

Fins torn of by danios is quite weird to me.
They are busy little buggers but not predators

 

[Fisharefriendsnotfoody]

I hope you're right.
I really thought I did everything right with slowly acclimatising the cardinals but I guess I still have lots to learn!

 

[Naughts]

Although danios are not normally aggressive it is not unheard of. A search of the forum would show other cases.
A danio could become aggressive if they are, or have been, kept in too small a group. Or it can happen when their tank is too small. They are very active fish and need a tank that is 90 cm long minimum.

 

[AquaBarb]

Ive had these two together with no problems before but it was in a bigger tank (105ltr)

I have seen the danios however cause damage to fins before with a dominant male injurying another group male.

I would guess here tank size maybe your issue

 

[Fisharefriendsnotfoody]

Thank you. I was hoping to upgrade soon but feeling a bit sad about it all at the minute!
Hopefully the excitement will return for me soon.

 

[Byron]

There are likely some contributing factors here. The tank is 53 liters (say 15 gallons) which is going to be very small for any danios which are very active swimmers. A larger group of the danios (of each species, zebra and leopard) would also benefit the fish, but there is no space for these. The cardinals are sedate fish, and would manage in this tank but on their own (or with similar small fish perhaps). Point here is, do not acquire more of any of these fish until you have worked out the issues.

 

[itiwhetu]

Cardinals were just the wrong choice of fish for your tank. That is why research is so important before you purchase any fish for your tank.

 

[Fisharefriendsnotfoody]

The remaining four currently seem to be doing very well so fingers crossed.
After Christmas I will be looking to upgrade the tank and then go from there with possible new additions.