Fish And Shrimp Together

Funny you should say that. I had 9 Sundadanios in with my shrimps; I assume they didn't eat the baby shrimps as I seem to have quite a few. The pygmy cories didn't make any impact on numbers either. The more recent habrosus cories don't seem to be eating baby cories to judge by the newly hatched ones I still have to rescue from the water change bucket.
I say had Sundadanios because they all died with a few days of each other with no apparent cause. One day they'd be fine, the next dead. So in my QT I currently have crystal shrimp and Boraras urophthalmoides. And I agree, they are smaller than adult cherry shrimps and a lot smaller than the crystals.

What species are your micro rasboras? Mine were sold as mosquito rasboras, which is a common name for B. brigittae but looking at photos on Seriously Fish, mine are definitely urophthalmoides.

Going by SF, urophthalmoides have a larger black spot at the base of the tail while brigittae have a much smaller black spot and red on the outer tips of the tail. It also comments that uroph's are often traded as brigittae because the shop can charge more, but mine only cost 85p each, less 10% for buying more than 5.
But I think we'll both have to wait a few weeks as a lot of fish only colour up properly once they've settled in.

I'm currently feeding the QT with finely crushed flakes (New Life Spectrum) and crushed Hikari Shrimp Cuisine. Of course the fish also eat the shrimp food and vice versa. Once they go in their permanent home, crushed sinking pellets, nominally for the cories, will be added to the mix. And I feed the 50 litre with frozen cyclops which the rasboras will be able to eat.

Mine are colouring up nicely. I have 2 brave ones that come to the front of the tank, the others mainly hide behind a plastic plant. I'll have to see if those are braver once they go in the 50 litre. The only downside is that I bought 10 but have no idea how many I still have. I think I've counted 8 at once but the other two could be hiding too well. With crystal shrimps also in the QT (same shop, tank in same rank) There wouldn't be much left to find if any have died.
Mine are orange rather than red. That could be because they are stressed or because they are indeed urophthalmoides.

Not having had leeches myself, I get the impression that they come in with plants or live food (as in alive not frozen).
I have found a reference saying that there are parasitic ones and harmless detritivores. It says the parasitic ones tend to be banded with green/yellow bars and the harmless types are brownish.

I would keep an eye out for them and remove any you see. The treatments, which range from salt to pretty nasty chemicals, won't do anything nice to the shrimps.

There are numerous types of leech and a simple colour comparison is meaningless. All leeches (if that's what you really have) are carnivores, none eat detritus. Some are fast swimming and may prey on fish and other swimming creatures, while others are much slower and eat things such as snails. Leeches move in a looping motion, they don't slide along, they have a sucker at each end and stretch out, attach the head sucker, then pull up the body, attach the rear sucker and so on. If yours don't move like that they're not leeches.

Ughhh. Shudders. Squash 'em ?
I had one tiny detritus worm the other day in the shrimp tank . Freaked me out. Haven't seen any more, even when I stirred up the substrate yesterday when doing a deep clean

There are numerous types of leech and a simple colour comparison is meaningless. All leeches (if that's what you really have) are carnivores, none eat detritus.

I did wonder about that but not being an expert in leeches I wasn't sure. Would the 'brown detritus eaters' be some different type of creature?
It's a long time since I studied zoology (44 years!) and can't remember too much about 'worms' be they annelids, nematodes or whatever 

Maybe use a variation of the snail trap? Put the shrimp/prawn in a jar with a lid, and punch holes in the lid from the outside so that the jagged bits point inwards. If any leeches did find their way inside it would make it easier to remove them.

All leeches (if that's what you really have) are carnivores, none eat detritus.

Pedants hat firmly on: Some leeches are carnivorous; This does not exclude them from eating detritus or scavenging. Most leeches are haematophagous; They eat blood. Generally, this precludes them from eating detritus.

Ugh!! 
How you can find these things interesting or have a favourite type is totally incomprehensible to me!
The good news is that I've not see any more. I'm going to try a snail trap as Sue suggested sometime this weekend and will post the results. If there's anything more disgusting in there, I'm giving up on the whole fish keeping thing. There's only so much my stomach can tolerate!