Inducing Shoaling?

[GrumpyJohn]

I've a 155l tank which holds 13 ember tetras, 9 neon green rasboras and a couple of ottos. When I first added the embers they often shoaled and looked pretty nice making their way around the tank. Being a fan of small fish I then added the rasboras and the result was a litteral mess of small fish. I've not since seen either (or all) shoal. 
 
They've been together for 3 or 4 days now - will they eventually settle into two or a complete shoal?
 
I'm thinking that maybe I need to induce shoaling somehow, maybe by adding one (or a pair) of larger fish. Sound feasible? If so, any suggestions as to what to consider?
 
I like both species of fish, but I regret the loss of shoaling which is why I went for smaller fish in the first place.
 
Your thoughts appreciated . . . . . . 
 
John

 

[TallTree01]

Not shoaling is a result of two things:
1) disease or poor water
OR
2) your fish are relaxed enough that they feel no threat in your tank.

My tetras rarely school and only do when I'm water changing or scaping. I think your fish are just relaxed. If you want schooling add a larger fish in there. Maybe a SA cichlid.

 

[TwoTankAmin]

Schooling is a defensive behavior. When the fish are terrified, the school may break as they decide hiding is the better option.
 
The fish need to perceive a threat that isn't really. I found an SAE or two worked well. basixally you want a larger sized fish that wont or can't eat the schooling fish.
 
I will say this, I have had a school of rummy nose Tetras in a 40 gal. tank for about 18 months and they still school with only spawning plecos in the tank. Their numbers are down to about 25+ from the earlier 40 or so.

 

[levahe]

The best shoaling fish (imo) are rummynose tetra, mine stay together all the time and are very entertaining to watch and have great character. The other tetras I have, neons and glow lights don't shoal together much at all.

 

[GrumpyJohn]

Hi and thanks for the replies. I'm not looking at replacing my Tetras/Rasboras but hoping to get them shoaling more. I did look at the Rummynose but they are bigger than I wanted.
 
What's an 'SAE'? 
 
Thanks

 

[TwoTankAmin]

Siamese Algae Eater- they get about 6 inches max. These are in the 3+ inch range (8+ cm).
 

They were all in there to get the bba out of the hairgrass.
 
This one is almost 6 inches- bad pic was aiming at the clowns.