Population Explosion!

[JoeG]

I have a 5 gallon tank that has seen a population explosion this summer. I fed the shrimp this morning some spirulina powder and counted 50+ floaters, five berried females, and one female releasing her fry. Each of the months this summer has seen a few floaters and berried females but this is definitely a record.

Feeding and some of the floaters:

[Dch48]

I had the same thing during the summer when the water temp hit 80-82. I only have a one gallon tank and there are shrimp everywhere now.

[JoeG]

It’s a good problem, right? The house is air conditioned and runs between 70-75 deg. I was thinking the longer amount of daylight had something to do with the breeding.

[JDillon]

So does the higher water temp promote breeding then? Wonder if I need to add a heater? I keep my house temp around 68 to 70 degrees year round. Any thoughts on this?

[Dch48]

Since my temperature has gone down to right about 70, I have not seen any more breeding activity. No floaters and no berried females. So for me, I would have to say that higher temps promote more breeding.

[JDillon]

I think I’m going to look into it and maybe do an experiment and see if raising the temp promotes breeding. My shrimps are mature now but haven’t seen any breeding though I have seen the molts. Will be interesting to try anyway. The challenge will be to find a small enough heater with a thermostat for a 1 gallon or less tank.

[ryangiggs]

I lived in a tropical country where it is 30-32deg C on avg in the day... so far my tanks had experienced a few breeding blooms when there was a prolonged raining period for around 1-2 weeks which brings down the avg temperature to ard 25-28... the breeding bloom coincided with this drop in temperature...

My theory is that a sudden and prolong drop or increase in temperature will encourage them to breed... so it probably doesn’t matter what temp it is... as long there is a slight difference in temperature for a pro long period... it will probably trigger them to breed...

Just my theory...

[Dch48]

Or, maybe 78-82F which is 26-28C is the ideal temp range for breeding. Warmer or cooler and they slow down or stop. That's my theory.

[JDillon]

I found a small enough heater with a thermostat and will start to test that theory shortly. Right now my office is at 70 and I’ll probably set the tank at 75 degrees Fahrenheit for a couple of weeks to see if that has any effect. If that doesn’t work I’ll try raising it to 78 for a couple weeks.

Question is how long after the temperature change did you see they population explosion?

[JoeG]

The one gallon tank set up in the basement two months ago has its first berried female today. The basement stays in the mid to upper 60’s year round. I just checked the temp and it is 69.3 deg. I will keep track of the breeding going on at the lower temps. There’s only 10 shrimp in the tank but we’ll see how it goes at temps consistently in the 60’s.

[Dch48]

It may also depend on food availability. Maybe , in my case, the biofilm and algae might grow faster at the higher temps. Or a longer period of daylight may affect them. Who knows? I can only go by what I have seen. I don't use a light timer on my tank so the light goes on and off whenever i do it which is rarely at the same time every day. There have been times when it stayed on until 3AM and other times when it didn't go on until 3 PM. I don't live on a schedule. I'm up when I'm up, and sleeping when I'm sleeping. It varies widely.

[JoeG]

Dch48 the only light the one gallon tank gets is the natural daylight. No light on this jar. They have plenty of algae, pretty consistent temperatures, in the 60’s, and natural light. It will be interesting to see how it works out in each season. Thank you very much for your comments.

The five gallon tank, on the other hand, has lights that are turned on and off manually. They are usually on at least 12 hours a day. These shrimp get supplemental feeding once per month. Alternating between freeze dried spirulina powder and shrimp pellets. The temperature of this tank is definitely higher then the basement tank. Stays in the 70’s.

[JoeG]

Update: Another female released fry today, we are 70+ floaters now! Counted 72 one time and 74 another, so we will just go with 70+. There are still four berried females to go.

[JoeG]

Update: counted 85+ floaters tonight. Only see two berried females and there is one still releasing some fry! Unbelievable.

[JoeG]

Update Saturday morning: count at least four berried females. The house has been cooler recently and the amount of daylight is shrinking each day so not sure if those two things had an effect on the amount of breeding going on. The only other possibility I can think of is that the number of females has grown and they are just ready to breed. The parameters of light and heat must still be within the range to breed and so they are going for it.