Cardinals and floating plants

[seangee]

Just an interesting observation...

My blackwater community tank has around 70% of the surface covered in floating plants. Last night I re-arranged my spray bar because I recently added pencil fish and wanted to create a quiet area at the surface for them. I did this by aiming half of the spray bar downwards. Usually my plants are all pushed to the front of the tank but now they are all on one side.

The pencilfish have appreciated the change and now spend most of their time in the roots where they used to often go down to get away from the current. But the cardinals behaviour is the most interesting. In the last 3 hours not one of them has come out from beneath the shelter of the plant canopy at any time. I assume they were doing this anyway but I never noticed because they were spread all along the length of the tank. I also assume that the cover provides a sense of security for the fish because the light level does not seem dramatically different to my eyes.

FWIW the glowlights spend most of the time under the plants but do occasionally venture out - although usually in amongst the vals. In general the cardinals are usually found slightly higher in the water than the glowlights. The corys don't seem to care.

So if you do keep tetras (or any blackwater fish) and don't have floating plants its certainly worth considering.

 

[Byron]

You are observing exactly what I so frequently write about...the need for floating plants with forest fish. It is always nice to have personal experiences confirming this or that.

In their habitat, Parachierodon axelrodi (cardinals) are always found in water that is 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. Observations also indicate that the shoal numbers vary according to the physical environment. When clustered around branches and such, the individual shoals tend to consist of five or six; in more open water without these branches, they are much larger, in the hundreds.

They may be an annual fish in nature, only living one season due to shortages of food. Open water is anathema to most forest fish, and when given the option they avoid it, even in the aquarium. Baensch suggested that they have a light phobia, which probably applies to many similar dark-water forest fish.

I have had similar experiences. My group of ten Congo Tetra in the 90g tend to stay just above mid tank, and there is a good cover of floating plants. During the water changes when I thin out the floaters (which can become a tangled mess across the entire surface) it is interesting that for several days following they remian further down in the water column. Their colouration also changes slightly, being darker when the floating plants are thicker.

 

[cowgirluntamed]

I absolutely love my floating plants! I have salvinia minima in two tanks and some amazon frogbit in one of them as well. I see all the fish up picking around the roots, even the cories! And seeing as how other plants so far dont seem to grow so well yet...the floaters have helped dramatically and give me less worry about water quality. They also helped me do an almost "instant" cycle as I let them get established first before I added fish. Gotta love floaters!

 

[seangee]

Love the way the Cories turn themselves upside down to forage through the roots. My Sids do it too.