Shy Cardinal Tetras?

Here's a quick backstory:

I've had this 15 gallon column tank for a while, it's dirted, and has lots of live plants.
(Take a look at my other topic, to show how much it has progressed:
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Anyway, I've had Cardinal Tetras in this tank for over 5 months now, and they would swim all over the place in the tank. It also housed a pair of German Blue Rams, which have died now. There are also some Pygmy Corydoras in there, and some Meh-quality Cherry Shrimp.

But lately, I've noticed that the Cardinals no longer swim around the tank, and basically just huddle in one little corner in the back, where I can hardly see them. They only come out during feeding time (at night), and shortly after that, they go back into hiding. I keep up with water changes, so I know for a fact that water quality isn't the issue. There's probably about 25 of them in there at the moment.

At first, I thought they were hiding because of the German Blue Rams, but since they're no longer there, and STILL hiding, I'm curious what else it could be. There are no signs of sickness, so there's that too.

Here's a picture of the tank... you can see some of the cardinal tetras in the bottom right corner, towards the back.
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Hmm about the only thing I could maybe think of is temps and oxygen levels. But oxygen should be fine with the plants. And I'm sure you have a good temp for all in this tank. The tank is beautiful. Hopefully something will draw them out.

Grasping at straws here but could there be something in any of the plants that they do not like? Odor, chemical release of any kind, anything like that?

I would do a water test just to make sure all parameters are where they should be.

OK..now the questions:
What is the water flow like in the tank?  Is there good circulation?  Lots of flow, slow flow?

How long do you leave the lights on?  I notice it is pretty bright (for the great plant growth) but possibly adding some floating plants would help making the fish feel more secure in a larger portion of the tank.

Is the spot they are hiding in providing them cover of any kind?  I have floaters in my column tank as well as a big log that provides cover and my fish seem to swim around a lot and not stay in one location in the tank.

I also have some other fish in the tank which I think provides some security in a way as my groups both spend time swimming the tank.

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Side note: you guys are making me sad I don't have a 15 gallon column. Maybe I'll upgrade my 10 gallon hex to one of these. Hex is hard to look into anyways without being distorted.

cichlid-gal wrote:I would do a water test just to make sure all parameters are where they should be.

OK..now the questions:
What is the water flow like in the tank?  Is there good circulation?  Lots of flow, slow flow?

How long do you leave the lights on?  I notice it is pretty bright (for the great plant growth) but possibly adding some floating plants would help making the fish feel more secure in a larger portion of the tank.

Is the spot they are hiding in providing them cover of any kind?  I have floaters in my column tank as well as a big log that provides cover and my fish seem to swim around a lot and not stay in one location in the tank.

I also have some other fish in the tank which I think provides some security in a way as my groups both spend time swimming the tank.

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Beautiful tank, Donna! As far as Ammonia, Nitrites, and Nitrates are concerned, Ammonia and Nitrites are at 0, and Nitrates are anywhere between 20ppm and rise up to 40-60 ppm before I do a water change. pH is at 7.1, General hardness and Carbonate Hardness is... well, I'm not sure. LOL... but I do know it's soft. =P

I have the lights on for 7 hours (turn on at 4pm, turn off at 11pm) I use two Panorama Freshwater LED Kits, by Ecoxotic, to light up my 15 gallon tank.

I'm not sure if cover is what's causing them to hide... my Red Tiger Lotus, shoots out floating lillies that end up blocking a lot of light, and they would still hide in the same spot. I just took this photo, and did a water change in the tank last night, so I trimmed all the floating lillies. The only thing I can think of that is "above" their hiding spot is the sponge intake that's on the filter intake. There's also driftwood, oriented vertically, that has a piece of anubias on it, which kinda acts like a "wall" so it leaves a clear space for the Cardinals to hide without anything obstructing their path.

Another thing I can think of, is that I did have other fish in the tank, but took them out because I thought it looked a bit crowded... those fish may have acted like dither fish to them, so by taking them out, I may have taken away that dithering effect... however, there are still shrimp and other fish that still swim around that I figred would still act as dither fish (gertrudae rainbows).

I don't think my plants are leaching out anything, that the fish might not like, as my other tanks have the same plants, and my cardinals in those other tanks seem to be doing well still. Quite odd! =P

As for flow... that maaaaay be an issue, it's currently using an Aquaclear 70, however, I did replace the impeller with an impeller from an Aquaclear 50, to reduce the flow, so... I'm not exactly sure if water flow is what's causing them to hide... even when I turn off the filter, they still stay in the same place.

hmmm...not sure either. Another way to reduce flow on the filters is to use a pop bottle, cut the middle portion (before where it starts to round down/up) and then cut that piece in half. Place that over the filter outflow and it will divert the flow sideways in the tank. I use this method in some of slower flow tanks.

I forgot to ask when the last time you did filter maintenance was and how often you do it? Hanging out by the intake sponges is usually a sign of stress in fish (I'm not sure what it is that they like about it but often cichlids will do that when they are stressed). I'd do a couple of extra water changes to get those nitrates down also. I think smaller fish are more susceptible to the higher nitrate concentrations than larger fish.

Im not sure if water flow is the case, because I've tried turning off the filter so that there's no flow at all, and the cardinals still stay in the same place. However, I do also have a method of baffling the outflow I usually just use canvas, the little holes help diffuse the water's current, thus reducing flow.

The fish look healthy, no signs of stress or any symptoms of ich, for that matter.

I keep my nitrates between 20-40ppm for my plants, fish don't seem to mind, and if I did a higher concentration of water changes, that would end up taking out too much of the nitrates, to where I would have to start dosing my plants with liquid ferts.

I'm starting to think that these cardinals are just being picky little snots. LOL

I had standard neons and green neons in my 10g tank. When I removed the standard neons for the same reason my green neons started doing the same thing. I haven't been too worried, but it does seems like peculiar behavior.

Poke wrote:Another thing I can think of, is that I did have other fish in the tank, but took them out because I thought it looked a bit crowded... those fish may have acted like dither fish to them, so by taking them out, I may have taken away that dithering effect... however, there are still shrimp and other fish that still swim around that I figred would still act as dither fish (gertrudae rainbows).

I've noticed this to be true effecting fish behavior. Many fish act different when you change stocking levels and become shy with less fish in their environment .


My fish friends and I don't like nitrates. But I don't think this is why they went shy on you.

Wait wait.. how could you not like nitrates, but still have awesome growing plants? lol!

I'm starting to think that my tank is under-stocked. I'll think of another type of fish I can add that will look nice in a 15 gallon column tank.

PokeSephiroth wrote:Wait wait.. how could you not like nitrates, but still have awesome growing plants? lol!

IDK. The 140 has tested 0 nitrates for a long time. One day about 2 years ago I read nitrates where bad, did research, experimented with plants and filtration. Made some modifications and now maintain 0. So whatever is going on in the filter media + all the plants = eat them all up...

PokeSephiroth wrote:
I'm starting to think that my tank is under-stocked. I'll think of another type of fish I can add that will look nice in a 15 gallon column tank.

This would be the way I would go too.

My Cardinals seem to love the PH a little lower, around 6.7-6.8, also they're not a huge fan of bright light I've learned.

If anything, my Cardinals may have already adjusted to our waters, so trying to change the water parameters would do more harm than good.

As for subdued lighting, that wouldn't explain how they used to be active, under the same circumstances. You'd think that by having less "aggressive" fish such as the German Blue Rams (which aren't very aggressive at all... for a dwarf cichlid, that is), that they would feel MORE comfortable in the tank.

When I watched that 30+ minute video on the planted discus tank with refugium he was pretty concerned about keeping the nitrites, nitrates and ammonia down even in the planted tanks. Hmm might be something to look in to.

It kinda seems a bit counter intuitive to keep nitrates as low as possible in a planted tank, you're literally taking away a plant's food source when you reduce the nitrates, plus 20ppm-40ppm isn't all that high anyway, to cause any impact on fish, as far as I know. Anything higher than 60ppm for an extended period, might cause some stress.

When you start dosing with ferts, you're basically introducing more nitrates into the tank, (such as Seachem's Nitrogen product), I think it's unnecessary unless you have a tank that's JUST plants, and no fish, where you end up having to dose ferts frequently.

Discus on the other hand, are very sensitive to nitrates, which is probably why that video talks about keeping nitrates down. Also, because discus require warmer water temperatures, it's trickier to keep plants with discus because plants don't usually like warmer water. There are some exceptions, but your plant selection narrows down quite a bit.

In my case, I've not changed anything in my 15 gallon tank for over 10 months or so, aside from stock levels. I'm starting to think that it is understocked. I'll try moving some of my neon tetras into the mix from my 55 gallon tank and see how that works. If nothing changes, I'll just catch all the neons and cardinals and put them back into the 55 gallon tank, which then opens up my 15 gallon tank to new fish! Hahaha, win-win!

Keep in mind cardinals come from the same waters as discus though ... same high temps and low nitrate tolerances compared to say neons.

And while high nitrates do cause fright behavior, if your nitrates were consistent the whole time it wouldn't explain the sudden hiding.   

dwarfpike wrote:
And while high nitrates do cause fright behavior, if your nitrates were consistent the whole time it wouldn't explain the sudden hiding.   

Precisely, which is why I'm leaning more towards the fact that there aren't any dither fish swimming in the tank anymore. They must think that the other "dither fish" have been eaten by some predator, or by some giant brown fish (my hand) HAH! =P

Which is also odd, since usually we (dwarf cichlid keepers) use cardinals as dithers to draw out the high temp dwarves like rams. I've never had to use dithers to draw out dithers before.   

LOL!! Interesting! =P man, my cardinals are just being snooty little buggers!
"I WANT A PONY!!"

Cardinal Tetras aren't shy anymore. It's about time! GOSH.

They look great. That's how my rasboras swim the tall tank too. What do you think did the trick with them?

Thanks Donna! First thing I did, was take out the piece of driftwood and Anubias that was attached to it, to allow for more swimming room. Then I trimmed some of the plants, and replanted some of them, along the edges for more "security" if that makes any sense... lol.

I also added more dither fish, which seemed to really do the trick. I guess they just ended up not liking being the only species of fish in that tank... Who would've thought? I was under the impression that they did better as a species only tank, but I was wrong. Hahahaha

PokeSephiroth wrote:Thanks Donna! First thing I did, was take out the piece of driftwood and Anubias that was attached to it, to allow for more swimming room. Then I trimmed some of the plants, and replanted some of them, along the edges for more "security" if that makes any sense... lol.

I also added more dither fish, which seemed to really do the trick. I guess they just ended up not liking being the only species of fish in that tank... Who would've thought? I was under the impression that they did better as a species only tank, but I was wrong. Hahahaha

Nice! Many fish species seem to do better when there is company in the tank.

Totally! I'm so happy my 15 gallon column is bustling with activity now! it's still one of my favorite tanks, because it's right next to my bed!