How long have you had them? Maybe they just need some time. Or there is something wrong with your water parameters. (I doubt it though)

Good luck

 

Maybe it is an aggression issue? I don't know about amano shrimp, but can they be threatening the tetras?

 

Neons dont school very well unless there is a threat. A lot of mine will just wander around under plants & my driftwood.

 

They should be swimming around. I have cardinal tetras with amanos in almost all my tanks, including one of my 29g tanks. My cardinals swim all over. The don't school, of course, but they don't hide either.

I'm wondering if the lack of other dither fish may be the problem? None of my tanks have just cardinals as the single fish (otos and amanos don't really count when it comes to swimming around kind of fish). That may be making the neons feel as if they are all alone. Maybe be a creepy feeling, as if all the other fish are gone.

Do you have any peaceful dither fish from another tank you could add to this tank to see if that helps any? It would need to be happy-go-lucky kind of fish that couldn't care less if there's danger in the area or not; it'll be swimming about. Maybe a small shoal of another tetra?

 

My cherry barbs kept my neons in a school. When I removed the cherries there was no other fish to keep them schooling so they returned to swimming randomly or hiding among the plants. They also seems to hide when the tank is only lightly planted or if there is too much open space, it seems.

 

I bet they are afraid of the Amanos! I have tetra with my amanos too but I dont have 20 Amanos with nothing else in the tank.

Think of how scary looking the must look to a small tetra! I would get some other dither fish to set an example for the tetras that it is ok to come out.

 

Is a 20 gallon too small for so many neons? You say it's heavily planted, maybe they are not actually hiding compared to let's say just chilling? Like other posters have said they don't school really like some tetras do.

 

I've put 25 amanos in my 29g tank with pelvicachromis and cardinal tetras. Didn't phase the tetras one bit. I generally keep 50-100 amanos in my larger tanks. Trust me, the tetras couldn't care less. As far as they're concerned, amanos are just another plant or rock. They don't even notice the amanos exist.

I realize that my tetras are cardinals and not neons, but I don't think there's that much difference between the two. Plus, none of my other tetras notice the amanos either.

 

what are the tnak parameters? they hide near wood or plants if parameters such as ammonia are not to their liking.

 

I noticed my bloodfins and redeye tetra hiding when there was ammonia in the water. Did a big water change and they were happy again

 

Ammonia, nitrite, nitrate all 0. The tank has been up and running for a while. I also use a whisper 60 PF filter rated at 300 gph and replaced all the useless media with additional bio rings for my 20 gallon.

These are the plants I have:

java moss
marimo moss
bacopa australis
banana plant
nymphaea lotus red
broad leaf ludwigia
dwarf HC
dwarf chainsword
cardinal plant
amazon sword compacta
clinoponium brownei
onion plant
rotala
water wisteria
4 different kinds of aponogeton hybrid (walmart bulbs)

I am starting to think lack of dither fish can definitely be a problem?

 

I think they school for food or out of fear, otherwise they're scurrying around the bottom of the substrate... until one finds something others will consider of interest and come together

 

My husband has 2 zebra's 1 neon & 1 black neon. He emptied half the tank yesterday afternoon & refilled it with new water. The tank is about 60+ litres water no plants mainly tall rocks & a sunken ship. Had the fish for 2 weeks now but when I put the water in the 1st time, I sprayed it removing the chlorine issue where as my husband did not, very absent minded he is, the man at the pet shop told us to do that as it removes the chlorine level. The neon now seems to hide away since this morning. Normal light fitting. Has anyone got any idea why it could be doing that?

 

A good suggestion so far is adding other dither fish, maybe other tetras. How long have you had the neons? I've read that if you spend more time near the tank, they'll get used to your movement and become more trusting eventually associating you with food. So feeding little and often may help, so you're at the tank more frequently.

Unless of course they're already hiding before you enter the room/they see you.

 

A good suggestion so far is adding other dither fish, maybe other tetras. How long have you had the neons? I've read that if you spend more time near the tank, they'll get used to your movement and become more trusting eventually associating you with food. So feeding little and often may help, then you'll be at the tank more frequently.

Unless of course they're already hiding before you enter the room/they see you.

 

Too much light or too much CO2 is my guess.