Endlers are also light orientated so light from another direction such as sun through the window shining through the tank walls can cause them to swim at nearly 90 degrees from vertical, I'm not saying it is this its just a thought
I find that using fish to cycle works better cause I don't like to put trust in those chemicals and I would only ever put chemicals in my tank for my plants and method blue if I have an outbreak of disease
Meth blue
I personally went down the fish cycle after my first few tanks I set up and found it to work better I don't like using chemicals uncles I really have to such as my frets and meth blue
I did a load of research when I first started out as my LFS advised me to use this chemical and I wasnt 100% sure I wanted to start putting things I didn't know about in the tank and I read on 1 site that it took someone almost 8 months to finish the cycle using this chemical he had the same...
I've found that using chemicles can actually make the cycling process take much longer for a fish less cycle I just dropped some flake food in the tank once a week only a little bit as the bacteria in the filter need a source of food just like anything else you want living in the tank