Good to hear! They are most likely hiding.
Why wouldn't the Opae Ula share his food? Because he was a little shellfish 
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It's been cold recently. What is the temperature in your tank. I think they can be more active in warmer temperatures. The average daytime temp in Hawaii during winter is still 78 F.
Why wouldn't the Opae Ula share his food? Because he was a little shellfish
Also if there is a large amount of algae in your tank then there is a good chance they may just be hiding and eating what is around them instead of coming out and hunting for food in the open.
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opae ula related wrote:It's been cold recently. What is the temperature in your tank. I think they can be more active in warmer temperatures. The average daytime temp in Hawaii during winter is still 78 F.
The normal temperature is 69 F, and the lowest it goes in the day in the coldest part of the tank (front bottom corners) is about 61 F. The tank is located in a privy with a boiler that usually keeps the temperature well above the outdoor temperature but I have noticed it turns off at certain times of day. There is also a 10W heater in the tank.
odin wrote:Also if there is a large amount of algae in your tank then there is a good chance they may just be hiding and eating what is around them instead of coming out and hunting for food in the open.
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opae ula related wrote:Good to hear! They are most likely hiding.It is possible that they are eating the algae. The few I do see around often have green in the front half body.
Last edited by Halocaridina on 22 Dec 2016 18:00, edited 2 times in total.
I don't know the exact temperature but I do know Opae Ula can die if it gets too cold. I personally have a 25w in my 2 gallon tanks and try to keep it on the green area in most thermometers. 
Why wouldn't the Opae Ula share his food? Because he was a little shellfish
I will try to upgrade my heater at some point. I remember they were more active on warm days during the summer when the water got close to 80 F.
Even these 25w ones I have can't keep up on cold days.
Why wouldn't the Opae Ula share his food? Because he was a little shellfish
I looked at the tank today and noticed a lot of the opae ula hide behind the heater - counted at least 7 on the back of it, plus one on the front.
The algae these days seems to be brown slime as opposed to green slime. Maybe a different species has become dominant? The brown slime has also grown on the central rock, where the green slime previously seemed not to grow. It has also covered the chaeto strands, making that appear brown as well. I have read that brown slime algae in marine aquariums means dinoflagellates, and these release toxins into the water. In freshwater aquariums, it means diatoms, but these usually only appear when the tank is still cycling since they need high levels of silicates. I would be surprised if my tank took over 5 months to cycle!
The algae these days seems to be brown slime as opposed to green slime. Maybe a different species has become dominant? The brown slime has also grown on the central rock, where the green slime previously seemed not to grow. It has also covered the chaeto strands, making that appear brown as well. I have read that brown slime algae in marine aquariums means dinoflagellates, and these release toxins into the water. In freshwater aquariums, it means diatoms, but these usually only appear when the tank is still cycling since they need high levels of silicates. I would be surprised if my tank took over 5 months to cycle!
Maybe they are hiding in the darkness of the heater/ its shadow or they are cold? You would have to eliminate what's troubling them with trial and error.
Picture of the brown slime?
Why wouldn't the Opae Ula share his food? Because he was a little shellfish