An eco system is a collection of things that together can form a balance and survive without outside help. This collection of living things will work together to florish. Making a small eco system is easy and very educational. The small contained eco systems are called eco-sphere. You can make one really easily and it should require very little maintenance. I did this the following manner:
Get a big glass pot (Eat some bottled vegetables, or simply buy one. I got a really big 5 liter pot for around 5 euros)
Get some decoration. I made two eco-spheres. One with seashells (which I first cleaned with fresh water) and one with lots of small pieces of sea glass.
Get some fresh water. Either use water from the tab (which require a day or two before adding any life to the eco-sphere) or get some water from river or a pond.
Get some small water plants from a local river or pond.
Get some living things. I have a couple of small snails (which came with the plants I got from the pond), and I have two shrimp in each eco-sphere. The shrimp are the only animals I bought in the store for 2.50 EUR each.
As an extra I went online and bought a moss ball (around 1 EUR) on AliExpress. This is a (small) ball of moss which serves as the perfect decoration, and sometimes the shrimp will be found sitting on the ball, cleaning it a bit.
Put your eco-sphere in a nice place where they will have daylight. This is needed for the plants to make oxigen and to grow. Do not place the eco-sphere in a place where it will be hit directly by the sun. This will heat up the water way to much and you will end up with cooked shrimp. It there is to much light entering your eco system you should notice an abundance of green or brown algea. This tells you you will need the eco-sphere to a place where it is a little bit less bright.
The shrimp can eat the algea that will grow in the eco-sphere. The snail(s) will also eat the algea and everything else they can find. The snails should also keep the glass clear. The poop from the snails and shrimp should function perfectly as food for the plants, and thats it. You just made yourself a really nice eco system!
You can also try an eco system without so much water. You will then need to add some dirt and some plants. I tried this a couple of times, but after a while the plants just got to big or simply died. Making a water based eco system is much easier.
Our shrimp has some young. In the mini eco system that we have there where two shrimp living. I think they are happy with their home, especially since I started giving them some extra food every day. They must be happy because they decided to have kids. When I was giving them their food today I noticed a very small animal on the glass. A closer observation made it clear it was a very small shrimp. Great!
Alan takes care of Chimbroek, a black and blue fish. Alex has Espinitas, a purple and blue fish and I got tho shrimp. We all got some pets. Alex and Alan’s fish need three grains of fish-food twice a day every other day. A good way to start developing a bit of responsibility.
Both fish have already been upgraded to version 2.0. The first versions were not a good buy and were floating up side down after two days already. They were changed without problem for better versions. Alex understood perfectly that the new Espinitas was a different fish. Alan had his doubts and noticed something had happened. He now keeps asking if his fish is dead again (even when its just sleeping) and he has figured out that sometimes dead fish revive with a bit more blueish color.
My shrimp are (for now) the easiest. I just put them in a big pot with a little plant and they do all the cleaning. I don’t think I even need to feed them.