-Self Sustaining Fishtank



This page is organized like a journal, it outlines the first sets of experiments I had with the tank, which took about five months.


In the beginning...
I bought the glass container which started it all, for $13 at a home decorating store. It's 2 feet tall and about 8 inches around at the widest point, so it holds about 1.5 gallons of water. The 'gravel' in the bottom is little blue glass pellets used in vases and things. It has a circle of white paper taped to the bottom to reflect some of the light in the tank back up.
      To start off the tank, I took care to get things going with microorganisms and let the water age a little before adding live critters. I filled up the tank with tap water and let it sit for almost a week. This let some of the bad stuff in the water get out or neutralize somewhat. Then I got some water from a local stream and dumped it in, I got some little bugs and some debris to help things start living in the water. Then I got plants, I took some water from my pond at home along with a couple of snails and some elodea, the idea again to start a little ecosystem going and get some oxygen in the water.
      After a couple days of it going, some cherry red shrimp arrived and were introduced. They seemed to take well to the new environment and came with a little java moss which started growing as well.

Growth and the first fish
After a few days of growing I got another plant in the mail, this one grew much slower than the other two, but would add some variety and some more biomass to the tank. Shortly after, I got a light with a 15W fluorescent bulb and stuck it on the side of the tank to help the plants grow. This was partly because it was very difficult to mount at the top, but because of the shape of the container and the height of it, mounting the light on the side seems to be the best way to illuminate the whole tank.
      I realized that the tank wasn't being filtered at all, and despite having only plants and scavengers, could probably use something to purify the water. I got a couple of Asian Golden Clams and set them free in the tank to help filter the water. It worked fairly well, and I have never had a water clarity problem.

The first fish
With the basic ecosystem of the tank setup and with some oxygen from the fast growing plants, I decided I wanted to try to add some fish. I began feeding the tank before they arrived to make sure there was plenty of nutrients for the plants and to get the plants growing. It wasn't quite enough....
      When the fish arrived (4 Lined Topminnows) they all congregated at the top, I thought they were topminnows so that was natural, but I soon realized this was because they weren't getting enough oxygen. The shrimp also began to move to the surface, but I had gotten the light going and did what I could to agitate the top water. It was a difficult place as I knew the plants would grow to suit the need, but did not know if it would be too late. Luckily, after a couple of days of growth (in a supersaturated CO2 environment, more than 3 inches a day per stalk) the fish started swimming in the rest of the tank, and there was enough oxygen for them to do as they pleased.
      I continued feeding them for some time, again to build up some biomass, and everything seemed to be going well, but I saw less and less of my shrimp. I began to think the fish were attacking them, as they were somewhat aggressive towards each other, and they continued to disappear. I later learned this was because the fish increased the nitrate levels of the bottom of the tank, and that shrimp are very sensitive to this.

Another try with shrimp
Without realizing the real cause of the loss of the cherry red shrimp, I decided I still wanted shrimp, and that larger ones would probably fare better. I bought some ghost shrimp and gave them a try in the tank. They lasted for about a week, slowly dieing off, in the same fashion. Their loss made a population explosion of planaria which looked like tiny white worms floating around in the tank.
      With no great scavengers and few snails, the tank began to get a lot of grime and algae on the sides of the tank, so I decided since shrimp didn't work, an algae eater would be a worthwhile investment. After some research on how big they can get, I decided on a dwarf bristlenose pleco, which stays small but is still fairly hearty. The pleco did a great job cleaning and seemed to get along with the other fish in the tank.... but it brought a disease with it.
      Within 2 days the sides were clean but the pleco was dead, and the disease killed the topminnows in a matter of a few days...

Recovery and the real test
After cleaning the tank, then several half water changes, I gave the tank some time to stabilize again. By now I had realized the cause of death of the shrimp and decided that another algae eater was not a viable option (they produce a lot more waste than normal fish of the same size). I decided to try again with cherry red shrimp, with no fish, and with snails to clean the sides. They established themselves fairly quickly, and the tank got cleaner with the snails. The java moss had grown in size, the elodea was green and healthy, and one of the other plants was still going despite being eaten by the fish and not growing as quickly as the others. The real test was just around the corner though...
      The tank had not been fed in about a month and was going strong, but I was going home for winter break, this meant the aquarium would be entirely on it's own for several weeks. I made sure to leave it on the windowsill to still get some light, and topped it off one last time, but I wasn't completely sure how well it would do.

Passed the test
I came back weeks later and was greeted by a tank in slight disarray, but for the most part a healthy one. There were many new baby snails and a couple fewer shrimp, but the tank survived 4 weeks on it's own, without even artificial light. To my surprise the shape of the tank let it loose only 2 inches of water off the top, I was expecting it to be half full or less.
      It has grown a little from that point until now, but is still mostly the same. There are lots of tiny organisms buzzing around the tank and the snails do a great job keeping it clean. I intend on trying fish again soon, but will go with fewer, smaller fish. I intend to raise a couple of killifish from eggs to keep the tank colorful and keep the plants in check, but not so many as to kill off the shrimp.



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4/16/08