Smallest diameter hole

[Chuck13]

I posted this question before and got a lot of helpful advice, which I really appreciated. However, I didn’t get a specific answer. I thought maybe someone might know so I’m giving it another shot. I apologize for the redundancy.

I made a shrimp cave out of a terracotta pot. I’m really happy with it. I’m hoping it will provide a good place for Bloody Mary shrimp to reproduce. 

The tank has amano shrimp, green neon tetras, and a scarlet basis also. 

What is the smallest diameter hole that will allow the Bloody Mary shrimp inside while also preventing the amanos and fish from entering?

Any help will be greatly appreciated.

Thanks 😊 

[JettsPapa]

I don't know that there is a definitive answer, but my best guess would be a 1/4" hole.  That may be too small for some adult neos, but if it was much larger then male amanos could probably get in.

Why are you concerned with excluding amanos?  It's my understanding that ghost shrimp will sometimes prey on neos, but I don't think amanos will.

[Guppysnail]

What I have seen from my neocaridina the mom will let the babies hatch in an area they can get into to hide. I had a rock pile adults could not get in the cracks. Mom would stay there while the babies hatched out and the shrimplettes would crawl in the cracks. Does not answer your exact question but I hope that helps. 

[Chuck13]

@JettsPapa
Good point! Any suggestions for the diameter if I only wanted to prevent the neons and Scarlet basis?

I appreciate your help 😊

Edited November 27, 2021 by Chuck13

[JettsPapa]

On 11/27/2021 at 2:42 PM, Chuck13 said:

@JettsPapa
Good point! Any suggestions for the diameter if I only wanted to prevent the neons and Scarlet basis?

I appreciate your help 😊

3/8", but please keep in mind that's just a semi-educated guess.

[Chuck13]

@JettsPapa

Of course! Thanks for your help.