Minimum number of shrimp per gallon?

[Aquarimax]

I currently have well over 100 opae'ula in a 3-gallon vase, and something like 50-70 in a 2-gallon container. Both containers are cylindrical, and the shrimp are very active and visible almost all the time. One container has a batch of floating babies right now.

I recently transferred 5 to a 10-gallon tank, and 6 to a 5.5 gallon tank, drip acclimating them. The new tanks had a thin layer of aragonite sand, lots of lava rock, and are well illuminated.

After the transfer, they were active and visible for a few hours, but it's been a couple of days now, and they haven't left their lava rock piles that I have seen.

I am wondering if they need "dither shrimp" of their own species.
(To explain the term, some species of fish in aquaria benefit from dither fish--an outgoing species that helps shy species to feel safe and thus come out into the open.)

Do opae'ula need a minimum density to help them feel confident in a similar manner? Or do they just need to get used to their new enclosures? It seems to me that when I first set up my other containers, they took a while to settle in...but it's been a while.

[KenCotigirl]

It has been my experience that when they are disturbed they are very active. In an established tank they settle down within a few hours. In a new tank they settle in a couple days. In a new tank they may stay hidden or remain on the substrate for a few weeks. Is it because they are scared? Because of they new and interesting food source? Do not know. Just seems to be their behavior.

[Aquarimax]

It has been my experience that when they are disturbed they are very active. In an established tank they settle down within a few hours. In a new tank they settle in a couple days. In a new tank they may stay hidden or remain on the substrate for a few weeks. Is it because they are scared? Because of they new and interesting food source? Do not know. Just seems to be their behavior.

It's good to know that their behavior in a new tank is normal. After day 1, I didn't see a single shrimp for about a week...then yesterday I saw 1 or 2 (difficult to say if it was the same shrimp or not) dart in and out of the lava rock for a couple of minutes. I may wait another week or two to introduce more, just to ensure that I don't tax the system with too heavy a bioload. The aquariums have both been set up for around a month, have visible algal growth, and a burgeoning population of MTS snails. I haven't fed the tanks yet, and I don't intend to do so until the opae'ula population is established and comfortable.

[Mustafa]

Shrimp are very economic creatures. They won't move around the tank unless they have to. Your tank probably has tons of food in your lava rock pile. They'll come out if the food there runs out. May take a while. Just don't feed them.

[Aquarimax]

Shrimp are very economic creatures. They won't move around the tank unless they have to. Your tank probably has tons of food in your lava rock pile. They'll come out if the food there runs out. May take a while. Just don't feed them.

I am now seeing some activity in the 5.5 gallon tank...1 or 2 shrimp at a time, not a lot, but something. Nothing in the 10 gallon yet. As you say, no feeding. It's funny, my two long-established cylindrical setups have tons of shrimp activity 24 /7.

[Mustafa]

Good. They'll come out more often over time. Just keep resisting the (possible) urge to feed.

[Aquarimax]

I added about 15-20 shrimp to the 5.5 gallon yesterday, and this morning I saw the most activity ever in that tank...lots of opae'ula milling around!

[Mustafa]

More shrimp means they more quickly eat whatever is growing in the tank and then run around looking for food. If they can just pick food where they stand, then they don't move much.

[Aquarimax]

I added about 40-50 shrimp to my 10 gallon, and the change was instantaneous and amazing. Shrimp are nearly always visible now...both the larger adults I had already added, and the juveniles I just added.

[Mustafa]

Told you.

[Aquarimax]

I noticed at least one berried female in one of the new tanks the other day. One of my established tanks has several berries females.

[Aquarimax]

At least six berried females, 2 of which are in the new 10 gallon tank.

[KenCotigirl]

Great news!

Ken

[Mustafa]

I love hearing about reproductive successes in this species! Awesome!

[Aquarimax]

I love hearing about reproductive successes in this species! Awesome!

Even though they started reproducing for me in 2007, the excitement never dims.
At least 3 of my 4 setups now have 1 or more berried females.