Science Experiment

Question
Hello,
Im in 11th grade and me and my partner have science project dealing with fish. In this case we have a 10-gallon tank and currently have 3 flamed tetras. I know, quite large for just those 3. We had 2 indian painted tetras beforehand-but they died 3 days after getting into the water & we also had one fiddler crab. That just died recently-which he lasted around 1 month.

So here is the expierment- We are not cleaning the tank. It has been 1 month without any cleaning. Occasionally we add clean water, due to the water evaporation. But we would like to see how the remaining tetras react to being in complete filth (green& brown algae cover just about everything) but in about 1 week we will start to restore the water. Little by little. We want to see how these fish react to this restoration. (slow restoration.) Can I ask your opinion on what you think might happen?

Answer
Kayla,
Honestly, I am a huge animal and fish lover, and do not approve of experimentation on any animal.
But I can tell you they most likely will not survive.
Cleaning a tank is not simply a matter or making it look nice, there are harmful and toxic chemicals that build up and the fish will suffer and become diseased, and eventually die.
Fish are constantly creating ammonia, by breathing, eating, pooping, etc. Ammonia is toxic to fish and when the are exposed to this harmful chemical for too long, they will perish.
That is why it is important to actually remove the water and replace it with new water.
By leaving the fish in a tank without doing water changes for a long amount of time they suffer.