Neon Tetras Frameless tank

[Bubbalou]

I started out my first 6 gal tank with 4 of these pretty, petite meanies. I upgraded to a 10 gal frameless tank which I cycled the new tank for quite sometime. My textras are still living and healthy. But there is one who continues to bully the smallest one who seems to swim by himself. also my frameless tank has a lid that is definitely not airtight because of the type of filter. I have not cycled their water but I do test it every couple weeks. My reason for not cycling is because this tank loses about 10% of water every week. I have only cleaned the gravel a couple of times. Should I be cycling? Should I get rid of the frameless tank?

 

[Colin_T]

Male neon tetras have a straight blue line, females have a kink about half way along the blue line. You might have a big male that is bullying a smaller male.

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If you increase the number of fish to at least 10, they should act more naturally and be less inclined to arguing. These fish normally occur in groups of thousands and having 4 in a tank is not good for them. Even 10 is stressful to them but they are much happier in larger groups.

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If you had a tank with an established biological filter, you can just move that filter onto the new tank and the new tank will be cycled.

Replacing some water each week does not cycle a tank. When water evaporates, it is only pure water that leaves the tank. All the nutrients and minerals are left behind and slowly build up to poison the fish.

You need to do a decent sized water change each week to keep nutrients down. I recommend a 75% water change and gravel cleaning the substrate each week to keep things clean.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.