Mystery of the missing cardinal tetras!

[illumnae]

I recently converted my 120 gallon tank into a Rio Negro/South American biotope set up with Heckels as the centrepiece fish. I previously had altum angels in the tank, but I've moved them into another tank. Some of the heckels had previously cohabited with the altums, and due to some poor planning on my part, had observed the altums making an expensive snack of existing cardinal tetras in the tank.

As I had previously kept cardinal tetras with my other discus with no problems, I proceeded to add cardinal tetras to this tank after removing the altums. They're my wife's favourite fish and they come from the Rio Negro, so I figured, hey now's a good time to put them in!

Over the past 2 weeks however, the cardinals have slowly diminished and now I have 0! Just wanted to check with others keeping heckels...do your discus also make a snack of cardinal tetras? Did my heckels pick up some bad habits from the altums? Or should I look to other causes for the disappearance of my cardinals?

[TankWatcher]

Seems I am lucky & my discus don't eat cardinals. They have even ignored tiny rainbow fish fry born in their tank.

But I don't think you can count on it not happening. I have ready many a thread where people have told of their discus eating cardinals. It seems pretty common that they do, but to me, it seems to depend on the particular discus. My cardinals reside happily with discus, but it sounds like yours might think them tasty snacks.

I'd suggest getting a bunch of small cardinals & growing them up to a good size in a separate tank, before you try them with your discus again.

[Darrell Ward]

Discus do sometimes eat them. I have also had them go down the overflow on my 240 gal. If you have a wet dry, check the overflow boxes and sump.

[erikc]

Hello Illuminae,

okay, sounds like you have a good sized tank for your Heckels (good move !).

However I have noticed that anything red, that hovers around the mouth of a WC will usually end up as a tasty snack. As I have said before, Heckels can move extremely fast when the are motivated !

The only sure way is to introduce the tertras with the hecekls when they are juveniles or fully satiated. Even then I wouldn't bet on it ...

[Discus Origins]

Sounds like a good mystery...as suggested in a prior post if you have an over flow or pump intake to check them. I've always kept cardinal tetras with my WC with no problems so maybe I have just been lucky so far.

[illumnae]

Nope no overflow. I'm using canister filters (A Fluval FX5 with flow turned WAY down and an Eheim ProII 2028) and both have suitably sized strainers to prevent the fish from being sucked in

[Bagxter]

Try to check them at the very morning... my neon tetras (not cardinals) started to disapper one by one and I discovered this:

One of my younger discus (2 inches) used to "wake up" before everyone else and was very active during early mornig and he literay hunted the neons (sometimes the runnynose tetras too) while they were still sleepy. He was too small to swallow them, but he bit them...

Sometimes the neons escaped and survided, but the problem was that the eyes of hte neons were particulary brillinat during this hour and became attractive to the discus... Sad but true... When they lose the eye, became an esay pray for the other discus too. I saw it several times!!! nothing that I could do....

They were 20 and were killed within a month... About 10 of them, dissapear before I could notice what was happening, I just sometimes saw the other discus feasting over a dead neon.

One interesting thing is that two of the runnynose tetras became one eyed. They are healty... eat well and swim perfectly (although sometimes miss the group dependig on what side thery are =))... It seems that they are tougher than the neons

The discus does not do that anymore, he is more... "mature" now. Ciclids are definitely amazing!!!

[saltydog]

I had the same happen to me in the beginning. I have bought a total of over 100 neons and cardinals combined and now have about 25 left and have had them now for about 3 months strong finally. But when I first started out the discus I bought had never been in a tank with other fish. So I think they took advantage of this after lights out or before lights on. Now though I think they are finally use to them and stay full enough to not be interested in them.

[neon]

I have tank raised discus and had 30 neon's and they picked off the neon one by one. My discus are not full grown yet and they will work together to eat neon's.

[bonghapster]

I have the same problem with my wilds and domestic. Any small bright color tetra gets eaten, neon, cardinals, rummy nose. They ignore black neon.