Wild Caught Cardinal Tetras

[Just Add Water]

I bought a small school of wild caught Cardinal Tetras a few months ago. Do they ever lose their skittishness? Mine dart away and hide in the same place whenever I walk across the room or approach to feed them. My tank always looks empty. Picture of when they’ve come out to eat.

 

[Byron]

Easily explained. You need floating plants, and a black background. A black background also helps all fish, it calms them.

This fish does not live in bright light. Baensch and Rhiel termed it a light phobia, which frankly applies to many Amazonian fish. Observations in their habitat showed that the water is always shaded by dense trees and either land vegetation or aquatic plants are always present. They congregate in groups amid aquatic plants, branches, or under overhanging land vegetation. During an investigation reported by Geisler & Annibal (1987), repeated observations in the biotopes of Paracheirodon axelrodi (cardinal tetra) indicated that the fish avoided the more strongly lit parts of their favourite waters and that their habitat ends almost to the centimeter on the border between shade and sunshine.

It is not easy from the photo, but I would suggest you have the Columbian form of this species. There is also a Brazilian form. They occur in separate geographical regions, never together. I'll give the external differences since you have the fish there to see more clearly.

Two forms of the cardinal tetra are known, one from the Rio Negro basin [the "Brazilian" form] and one from the upper Rio Orinoco basin in Columbia. In the late 1990's, Dr. Jacques Gery suggested that they might differ morphologically, and be distinct species, sub-species or variants; more recent studies are suggesting the latter. They are outwardly recognizable in three ways. On the Columbian form, the neon line ends at the adipose fin, the red colouration does not extend as far under the belly so there is slightly more white, and the fish is chunkier in general build. By contrast, the neon line on the Brazilian form extends below the adipose fin and is straighter in appearance, the red extends slightly further down on the belly, and the fish is more slender and thus appears longer than the Columbian form.​

 

[AlexT]

I've never seen Cardinal Tetra's happy in anything but lush planted aquariums. But I don't have a huge sample size to draw on to be honest.

 

[Just Add Water]

Thank you! I can get a black background right away. I did cut my lights over 50% and they do come out and swim when the room is still. I’ll look into getting some surface plants too. I’m excited to see if I can tell the difference in species. Very cool information. Thank you.

 

[Byron]

Thank you! I can get a black background right away. I did cut my lights over 50% and they do come out and swim when the room is still. I’ll look into getting some surface plants too. I’m excited to see if I can tell the difference in species. Very cool information. Thank you.

The easiest black background is construction paper. It is not glossy (this bothers fish), and it makes the space seem larger and settles fish more. Floating plants, like Frogbit, Water Sprite.

 

[Colin_T]

Fish will also act nervous and skittish, and hide when you enter the room if they aren't use to things moving around them. This happens a lot when aquariums are in bedrooms and the only time you go into the room is to feed them or go to bed. The fish see you enter the room and think predator, and they take off and hide.

To fix the problem (besides what Byron suggested) you can have a small television on in the room. You don't need the sound but the flickering lights and movement on the screen will help the fish get use to movement around them.

You can also use a small oscillating fan with some streamers tied to the front cage. Make the streamers about 12-18 inches long and just let them wave about as the fan blows. Having a mobile in the room with the fan can also add movement.

Using these in addition to floating plants and a picture on the back of the tank will make a huge difference to the fish and you should eventually be able to walk into the room and the fish will continue swimming out in the open.

 

[Just Add Water]

Yep, Colombian form!

 

[Just Add Water]

Fish will also act nervous and skittish, and hide when you enter the room if they aren't use to things moving around them. This happens a lot when aquariums are in bedrooms and the only time you go into the room is to feed them or go to bed. The fish see you enter the room and think predator, and they take off and hide.

To fix the problem (besides what Byron suggested) you can have a small television on in the room. You don't need the sound but the flickering lights and movement on the screen will help the fish get use to movement around them.

You can also use a small oscillating fan with some streamers tied to the front cage. Make the streamers about 12-18 inches long and just let them wave about as the fan blows. Having a mobile in the room with the fan can also add movement.

Using these in addition to floating plants and a picture on the back of the tank will make a huge difference to the fish and you should eventually be able to walk into the room and the fish will continue swimming out in the open.

They are in my living room. The ceiling fan is always on, but they probably don’t see that. But it’s just me and my husband. The tv is on in the evening, but their lights are on a sundown dimmer. During the day I’m around cleaning and doing laundry, etc. I will add more plants and a background. I hope they start to see me as the feeder and get excited to see me like my last fish did.

 

[seangee]

As an idea of what they mean by plants the pic below is my cardinal tetra tank. They should also be in a larger group than 6, at least 12 (I have around 60 but it is a bigger tank)

 

[AlexT]

As an idea of what they mean by plants the pic below is my cardinal tetra tank. They should also be in a larger group than 6, at least 12 (I have around 60 but it is a bigger tank)

Is the picture there mate? I can't see it. Might be me as I am on my phone

 

[seangee]

Is the picture there mate? I can't see it. Might be me as I am on my phone

Yeah its my signature. Only seems to show on my phone when I turn it sideways (landscape)

 

[Just Add Water]

Thank you all for your help!! Here is my updated aquarium.
I added Amazon Swords and Red Root Floaters. I rearranged the Java Ferns and moved the faux driftwood.

 

[Colin_T]

How are the fish acting now, are they still skittish or are they settling down?

 

[Just Add Water]

How are the fish acting now, are they still skittish or are they settling down?

They are still skittish. They like checking out the new arrangement and have been playing in and around the driftwood more, but as soon as I walk across the room they all dart away to their favorite back corner. I’m still the scary predator, hoping one day I’ll be their favorite food lady!