# Shrimp Behavior and Population Growth



## Chandavi (Jun 12, 2012)

Good evening everyone! It has been a while since I posted anything about my 5 gallon, mainly because everything has been smooth sailing. The eight _corydoras pygmaeus_ are doing very well and have remained active and healthy since their introduction to the aquarium. Lately, the cherry shrimp in the aquarium have been more interesting due to a few developments. Originally I had two cherry shrimp, which were introduced along with the cories. Recently I added three more, one of which was berried when I bought her. I believe all 5 are still around, but it is difficult to tell since they like to hide in the dark sheltered areas at times - I see 3 at a time on a regular basis, but the other two could easily be hiding. Now, on to the interesting bit!

*Interesting Situation #1*
Recently, I have noticed that one of my shrimp has developed very bold and interesting behavior. She has grown to about the same size as the cories, and no longer has any reservations about competing with them on their food pellet! She jumps right into the mix while they are feeding and sometimes even tries to carry the pellet away while the cories are eating. They don't seem to mind - they keep on sucking on it even while it is moving. Today, I noticed something even more bold! I dropped in the usual sinking shrimp pellet (ironic, I know) and it began to bob up and down in the water column while it began to hydrate. She was sitting on a plant leaf nearby, saw it drifting past, decided to leap out and grab it, then "tackled" it to the floor of the aquarium. She rolled around and ate on it for a good 30 seconds before the cories noticed and joined in. Has anyone else experienced this sort of behavior? So far I believe only one of the shrimp is acting this way. Is this to be expected, or is she just an oddball? I've noticed that she also has a very strong and vibrant red color - could this vivid color and attitude be related?
*
Interesting Situation #2*
As I mentioned, one of the shrimp I purchased about a month ago was berried when I bought her, and I also noticed that one of my original two was berried at around the same time. The eggs disappeared about a week or so ago, so I thought nothing of it. Then, this morning, I turned on my tank light. Climbing all over the walls of my tank were baby shrimplets! I counted 30 in total, but there are likely more hiding in the gravel or under the rock shelter. They are about as big around as a 0.7mm pencil lead, and are about 1/8 of an inch long. They are clearly grazing on the green algae growing on the tank walls, which is fine by me. The little army combined seems to actually be making a dent in it. To think I was about to do a big water change and wipe it all down! The cories do not seem interested in them at all, but I have not yet seen a head-to-head encounter along the tank floor. Now, for the moment this is quite cool, but I do have some concerns about the long-term situation. 

This is a planted and filtered 5 gallon hex (details HERE) with stable water parameters; the plants assimilate the nitrates and my BBCs have kept ammonia and nitrites at 0 since introducing my livestock after a fishless cycle. I do water changes of course, but the nitrogen chemistry is not the driving factor behind them - nice and stable. In any case, it is only a 5 gallon and already has eight 3/4" to 1" pygmy cories in it. I can't help but wonder what my course of action would have to be if all thirty of these shrimp grow to full size. I highly doubt I could keep them all in the aquarium. That would be some serious overcrowding and I don't want to subject either the fish or shrimp to that. In you guys' experience, how many shrimp survive from the 1/8" stage to become fully-grown adults? If most of them will indeed grow up, what suggestions do you have for me on dealing with this? What suggestions do you have for the shrimp I have to move out of the tank?

I originally set up the system hoping to have a self-sustaining shrimp population, but this... this is ridiculous. I guess I got more than I bargained for!*r2


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## graybot (Apr 24, 2011)

The feeding behavior is expected- most shrimp are greedy eaters and will spar with anything they do not perceive to be a threat for food. The threat perception seems tied to the relative size of the shrimp and its competition. For color, I have found that cherry shrimp turn far more vibrant if they are fed regularly rather than being left to eat microorganisms and algae or scraps left from other fish.

8 cories in a 5g sounds very overstocked, and with a hex tank it sounds cramped. Cories like to dash around and "play"... I would consider a 10g minimum for dwarf cories, especially at that number.


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## graybot (Apr 24, 2011)

You don't have to worry much about overstocking the cherry shrimp, they have such a low bio load that you could maintain a colony of 50 or so full sized shrimp in that 5g. Perhaps move the cories to something larger and let the shrimp go nuts in the current tank.


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