DIY Aquarium of plastic bottle for guppy fry

Supplies: 2 liter or more (the bigger the better) plastic bottle and plastic tube.

Remove all stickers and wash the bottle.

Cut off the top part of the bottle.

Make a hole using a hot soldering iron about 8 - 10 cm away from the cut.

Cut aslant the end of the tube.

Insert the tube through the hole in the bottle. Make sure the end of the tube rests on the bottom of the bottle.

Place the bottle horizontally. Hold the tube vertically. It should prevent twisting of the tube in the hot spot.

Apply hot glue to seal the hole around the tube.

Hold the tube until the glue cools down. My bottle got bent because of the heat.

Pull the other end of the tube through handles of a paper clip.

Fix the paper clip to the edge of the bottle.

Cut the tube to a desirable length. I cut it about twice the length of the bottle in this example.

Place a rock to hold down the tube.

We have made a simplified version of the aquarium of a plastic bottle.

Fill the aquarium with water and let it stand for 24 hours. I use water from the aquarium where baby fish were born.

Add plants, snails, and guppy fry (babies). I put together 7 babies in this example.

To remove residue from the aquarium, you have to lower the end of the tube below water level. The lower the end of the tube, the faster the water will drain.

Add clean water as necessary. 

Let the guppy babies grow until it's safe to move them to the aquarium with adult guppies.

It may help you to breed guppies of different colors and with fins of various shapes. Sooner or later your aquarium (no matter how large it is) will be overcrowded. Here we come to a question. What do you do with all the spare fish? It would be useful to know your solutions. Please post your answers in the comments to this video. 

My previous videos about making aquariums of plastic bottles brought various (positive and negative) feedback from viewers. It is necessary to do more research and have experimental proof before making any statements. I will keep you updated on the results of my experiments.

In the line of my experiments, it would be interesting to breed a smaller size guppies strain suitable for small aquariums. The smallest guppy males are about 1.5 cm and females about 3 cm. Is it possible using selective breeding to grow a strain of guppies of an even smaller size? It is challenging. By selecting the desirable, in this case, the smallest fish, we also pick the weakest that may not survive. I would appreciate your expertise, advice, and constructive ideas. Please comment.
Have fun and happy fish :)