Why Do My Tetras Hide?

I have a heavily planted 15 gallon tank with 6 neons and 8 glowlight tetras. It also has 3 glofish tetras, 1 Green Fire tetra (last of a group) and 2 Emerald Corys.

It's a heavy stocking, but I change 40% of the water every 2 - 3 days and they all eat well, etc. All parameters good.

The only fish that swim around freely are the corys - they are usually digging through everything looking for food- they are totally unafraid- and my Green Fire tetra who, as he always has, swims around in the middle.

The glowfish tetras used to swim more in the middle, but they've slowly joined the other tetra kind of hiding in the plants. They are all in a room that is heavily used, they see me open the lid and they come out for food, but otherwise they stay down there in plantville.

Juxtapose that with the 20 Ember tetras and the 10 Green Fire tetra I have in my 75 gallon tank- they are ALL over the place- much of the day you'd be hard pressed to call them a shoal, then a couple of times a day, they all seem to come together for PT- doing laps of the tank- first at the back, then at the front LOL. It's fun to watch.

Why are the fish in my little tank so shy? Another note- the fish in the little tank have all been there at least 6 months, and some over 1 year.

I've considered moving the Green Fire tetra to the big tank to be with buddies. He's very hard to catch, though. So far, he remains. I wonder if I should move either the neons or the glowlight to the other tank? I don't know....they all get along and they hang out there together in the plants, so I don't think they're getting in each other's way- there's the whole middle and top left for just the one Green Fire tetra to roam. He doesn't pick at any of them, either.

Surely because of their small numbers. They feel the safest when they are completely surrounded by their peers.

When I want to catch fishes that are ultra elusive. I put the net in the tank and leave it there until they get used to it. Watching often that no one gets stuck in it during this time.

Have you any over head cover i.e floating plants.

I find this really makes a big difference to small fish like yours

AquaBarb said:

Have you any over head cover i.e floating plants.

I find this really makes a big difference to small fish like yours

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That's a good idea, AquaBarb. I have some in my big tank- I'll take a few and see if they'll spread in the little one- I'll need to re-direct the flow a bit to keep it off the surface, but should be fine. Thanks!!!

MaloK said:

Surely because of their small numbers. They feel the safest when they are completely surrounded by their peers.

When I want to catch fishes that are ultra elusive. I put the net in the tank and leave it there until they get used to it. Watching often that no one gets stuck in it during this time.

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yeah, I guess you're right, but I've had less numbers of neons that were out and about all the time. This is the first time I've had glowlights, so no experience there.

Good idea with the net- I'll give it a try to see if I can move the Green Fire to be with his brethren.

It can be caused by poor water quality or chemicals in the water. A bright tank, lack of hiding places, low numbers of fish or any number of other things.

A picture of entire aquarium can show things that might need tweaking.

I agree, they love to have moderate lightning and dark places to rest.

They also require a long photo period 12-14 hours a day and complete darkness during the night.

Colin_T said:

It can be caused by poor water quality or chemicals in the water.

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Water quality is great- TDS is about 177 and all parameters are good- I keep the PH about 6.8.

MaloK said:

moderate lightning and dark places to rest.

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Lots of dark places- that's where they are most of the time LOL. I also keep the lights on (simple LED light that came with the tank) for 10 hours a day- I could up it by 2 hours if that might help.

See pic below - most recent- sorry for the cat. Maybe he's part of the problem- the Corys ignore him. He's only up there maybe once a day, though. Under the anubias plants is a big open square where there is room to hang out and they can (and do) swim through the leaves of the sword and under/behind it.

Depending on the kind of tetra, they need light or even less light. In free nature some tetra species live in dark waters. In mangrove territories, they can choose to swim in dark or clear water. When tetras stay in planted areas, they do it to take some rest or to breed. In worst cases to hide from something.

MuddyWaters said:

Water quality is great- TDS is about 177 and all parameters are good- I keep the PH about 6.8.


Lots of dark places- that's where they are most of the time LOL. I also keep the lights on (simple LED light that came with the tank) for 10 hours a day- I could up it by 2 hours if that might help.

See pic below - most recent- sorry for the cat. Maybe he's part of the problem- the Corys ignore him. He's only up there maybe once a day, though. Under the anubias plants is a big open square where there is room to hang out and they can (and do) swim through the leaves of the sword and under/behind it.
View attachment 333355

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I absolutely love every cat I see, Loll... Beautiful !!!

Seems a little bright... Looks like AquaBarb suggestion would be your best bet. You can lower the water level a bit and add some cover in there.

Why?

If you are a small fish in a big world, everything wants to eat you. Birds are a major enemy. So as an aquarist, you have to look at that fear. Chances are, those fish do not want to be seen, from above. If the plants get to the surface and start arching over and creating shade, then they will be more adventurous.
Plants that have broad leaves about halfway, or less, up the tank will also provide security.
Once they know they can hide, they won't feel the need to.

Your water sounds good. The cat might trigger the odd, startled release of fear/warning hormones, but with regular water changes, that's taken care of.

How often does the cat jump up next to the tank?
I would put money on it being the cat, and to a lesser extent, no floating plants.

You need to keep the cat off there. If it bumps the tank it can startle the fish. Having a huge shadow jump onto or next to your home will stress any animal, including fish.

That's a big cat next to a small tank with tiny fish that have nowhere to flew when the monster appears next door.

MaloK said:

Seems a little bright... Looks like AquaBarb suggestion would be your best bet.

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Yeah- it's not as bright now as it has been- I think my light is going, though. Not the way I want to turn it down. I did grab a few red root floaters from the other tank and put them in there, though, so that should help.

GaryE said:

from above. If the plants get to the surface and start arching over and creating shade, then they will be more adventurous.

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Yeah- never thought about putting plants on top. I might put some water sprite in there too and let it get big- might help shade the top some.

Colin_T said:

You need to keep the cat off there.

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Yeah- Colin_T you are right, but man, that cat outsmarts me all the time. I have given up the fight with this tank. He literally sleeps on top of it. He likes to mess with the Corys who couldn't care less about him, and I have to admit it's kind of fun watching him try to grab them LOL.

He learned to get up on my 75 gallon too, which I have built a fort of books around to prevent. My other cat is more agile and will still find a way up there sometimes, but she does it a lot less.

Everyone: Thanks for the tips- much appreciated- I've been wondering about this for awhile- not sure why I'm just now asking

Put a picture on the side of the tank that the cat sits next to. Then at least the fish won't see a big shadow appear next to them.

Putting something on the table so the cat can't get on it should be easy enough to do. Otherwise a small water pistol and water and tell the cat to get off. If it doesn't, give it a quick squirt.

Moth balls are meant to repel cats and I think citronella does too.

You can't leave the cat there tho, it will shorten the lives of the fish.

UPDATE - Moved all the fish and - magic!!!

So, I messed around with my small tank trying different things to see if I could entice a behavior change in the fish residing there. No luck.

So, I got tired of staring at water and plants and I moved all of them to the big tank (except the 1 oto I have in there- he's impossible to catch).

Suddenly, they are all swimming around in the front of the tank, having a ball. The neons and the glowlights now are having a ball! Maybe they just felt cramped in the 15 gallon because of all the plants? Who knows- I'm very happy to be able to watch my fish now and they seem very happy with their new digs. Even when I put my face up to the tank (which I love to do sometimes to see details on the fish as they swim by) they are not bothered at all.

Here are a couple of pics of the neons together- the glowlights are all over the place, not really sticking together.