It Pays to Be Careful When Deactivating a Tank

As noted in “Thoughts on Filtration in Opae’ula Tanks” (11/26/15), I deactivated some of my tanks to a manageable few. This is the note that I appended to the post on filtration:

[11/26/15] This past week, I decided to reduce the number of tanks by eliminating the two 5-gallons. I moved the colonies into the 18-gallon. Salt crusting had been an ongoing problem, and reducing the turbulence and lowering the water level didn’t seem to work.

Update 11/27/15: A couple months ago, I found a slow leak in the 2.5-gallon tank and used the small colony to start the Oblong 1.5-gallon tank. Thus, as of this date, I’m running 4 tanks: 10-gallon, 18-gallon, 1.5-gallon, and 1-gallon.

One of the tanks I reluctantly decided to eliminate was the 5-gallon Fluval Chi, my first opae’ula tank. After removing the coral condo and moving the colony to the 18-gallon, I decided to leave the tank running for a few days just in case I missed some of the juveniles. There were some berried females just before I decided to decommission this tank, so I decided to take this precaution.


This is the 5-gallon Fluval-Chi as it is today, a barebones version of what it was in its heyday. The towel prevents overexposure from the sun. Without the condo, the opae need some relief from the intense light.

I’m glad I waited before emptying the water out of the tank. I noticed a few tiny specks moving about in the tank (see the red circle in the photo below and enlargement below that) and realized some of the juveniles had been left behind. They were too small to catch with a net. Also, they hid within the gravel, and trying to capture them would mean also scooping the gravel around them, and that would definitely crush them. So I decided to wait until they grew a little bigger before trying to net and move them.

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I’ve left the tank in this state since I’m planning to empty it once the juveniles are moved out. One of them is visible in this photo. See the area circled in red and the blow-up below.

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A zoom in of the area circled in red in the photo above.

At first, I thought there was only one juvenile left in the tank. However, over time, I’ve seen two others. There may be others that I haven’t seen.

Even partially filled, salt crusting in this tank remains a serious problem, so I’m still planning to empty it out and use it for something else. In the meantime, I hope the little guys survive and grow up quickly so I can catch them and move them into a better environment.

These juveniles are special since I know they are “natives,” born in my first tank. The others born in this and other tanks are mixed in with the “immigrant” population so I can’t tell them apart. Thus, I may try to keep them together in a smaller container, perhaps a second Nishijima-type bottle.

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3 Responses to It Pays to Be Careful When Deactivating a Tank

  1. BoEn Liu says:

    My first tank, being the inexperienced hobbyist, I removed all the adults and dumped out all the water in the tank for a full wash since I thought the tank was slightly dirty. After sifting through the gravel and decor, I started to notice dead, crushed juveniles among the gravel.

    At the time, I was always away for college so I solemnly ever touched/observed the tank, probably one every three months. I never saw a berried female so the idea of juveniles in my tank was never on my mind.

    At the end of the day after finishing the cleaning of tank, I remember counting up to fourteen or fifteen juveniles within the gravel. I ended up setting up a smaller fish bowl–a 3.5 gallon fish bowl for a beta I had when I was younger–and transferred the remaining adult opae’ula there. In hindsight, I wish I did what you’re doing currently to my first tank.


    • JimS says:

      Hi BoEn Liu. I’m sorry to hear about the loss of your juveniles in the cleaning process. In the past, I did a number of changes in my now decommissioned tanks, and I didn’t think to check for juveniles. Thus, I probably inadvertently lost some that were hiding in the gravel. I also learned to be careful when removing larger rocks from the tank because one or two will cling to them and be lifted out of the tank. In one instance, after removing all the rocks that formed a condo and placing them in a container, I decided to fill the shallow container with tap water and remove the rocks one at a time after swishing them around in the water. The thought that some might have been clinging to the rocks occurred to me. After removing all the rocks, I found one shrimp in the container. I caught it with a net and placed it in the tank with the others. The problem is that I had dismantled similar condos in the past without taking this precaution and probably lost a few shrimp. Also, I didn’t check for tiny juveniles back then, so I might’ve lost some of those as well. Now, whenever I dismantle a condo, I swish each rock in the tank before removing it to make sure that shrimps aren’t clinging to it. There’s still so much we need to learn about these little guys.


      • BoEn Liu says:

        “There’s still so much we need to learn about these little guys.”
        i can’t tell you how much i agree with this statement.


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