Is it common for Cardinal Tetra to be aggressive

[Porsche8855]

Hi everyone,

I added 4 fire shrimps into my 55g tank with about 55 Cardinal Tetra.

The immediate reaction was like a shoal of piranha chasing and attempting to attack the poor shrimps.

I took immediate action and removed the shrimps.

Is this common? Do I need to feed the tetra more?

Your enlightenment on this is appreciated.

[Urban Aquaria]

I guess you put 4 micro-prey in a tank with 55 micro-predators... odds of 1 vs 13, those type of ratios are usually not favorable for the prey animals.

Tetras are part of the piranha family, they do have the hunting instinct and own a nice set of teeth too:



Photo Source: http://www.planetinverts.com/peter_maguire_photos.html

[Urban Aquaria]

On a more helpful note... it depends on the tank setup and whether the fishes are familiar with the shrimps. Usually tetras and shrimps can co-exist in the same tank without issues, some newborn shrimplets may get eaten, but the adult shrimps are not disturbed.

In your case, i guess the tetras somehow view the shrimps as food and there are probably not much hiding places for the shrimps, so they keep getting harassed. The bright red color of fire red shrimps don't help much in terms of camouflage either.

Feeding the tetras well could help reduce their hunting behavior (fishes which are hungry will be more likely to turn on live prey), though its a fine line between feeding enough and overfeeding.

[Dscheng]

Wa..55 tetra vs 5 fire red shrimp.. Confirm get attack. As for my tank, i got 20 tetra and other fishes. But my shrimp population is like 200+

[Dscheng]

I guess you put 4 micro-prey in a tank with 55 micro-predators... odds of 1 vs 13, those type of ratios are usually not favorable for the prey animals.

Tetras are part of the piranha family, they do have the hunting instinct and own a nice set of teeth too:



Photo Source: http://www.planetinverts.com/peter_maguire_photos.html

What... that sharp set of teeth.. i always thought they are peaceful.

[Porsche8855]

Really sharp set of teeth.

Thanks for all the pointers.

Maybe will move to other algae eaters. Any recommendation for my set up?

My tank picture is enclosed for reference

[Porsche8855]

Sorry here is my tank setup.

[Urban Aquaria]

Actually, you can still use shrimps... maybe use larger ones like Amano shrimps (buy those bigger 5-6cm length ones), their large size should help deter harassment, and they are super efficient algae eaters too.

The other option is to add 100-150+ small shrimps (those cheap malayan or cherry shrimps sold in bulk bags would be ideal), a percentage of them may get harassed initially and eaten, but a good number of them should be able to hide and survive. The fishes should gradually get accustomed to them over time and "hopefully" cease to view them as prey/food.

You could also use lots of fire red shrimps too (looks nicer), but the costs will be much higher.

[Porsche8855]

Thanks. Interesting proposal on the overloading of small shrimps.

It got me thinking.

[fstyle28]

I learnt something new today.

[Clamence]

Try feeding the tetras first before introducing the shrimps. They may mistake the shrimp for food during the first day or so but after that they shouldnt bother your shrimps

[BFG]

You could introduce the shrimp during the night while the lights are off. Release them amongst the plants are ideal.

[Ralph]

HOLY!!! Part of the piranha family? No wonder my cardinal tetras feed like them. The speed with which they dash in and rip the feed apart, often leaving nothing left even before my betta had a single bite.

I guess you put 4 micro-prey in a tank with 55 micro-predators... odds of 1 vs 13, those type of ratios are usually not favorable for the prey animals.

Tetras are part of the piranha family, they do have the hunting instinct and own a nice set of teeth too:



Photo Source: http://www.planetinverts.com/peter_maguire_photos.html

[Vanilla]

Not only shrimps, even new fishes can becomes fish food if they introduce the wrong way. I have experience, my fishes attacking new fish upon dropping into the tank when they are very hungry and active awaiting for food . They though its fish food.. After a while they will realize it's not fish food but New fish suffer injuries n shock...

hence, best to feed to distract. Else introduce the fish in a gentle way from your fishes.
if your tank is smaller, the problem maybe more prominent.
Cheers!