I have 4 new 1 y/o zebra plecos getting settled in their own 20g (long) aquarium. I also had one algae eating pleco in there to keep the algae under control, but upon checking the tank today i found the algae eating pleco dead...

Here is what the water test showed. (keeping in mind this is about a month old tank, and i filled it with tap water that i treated with water conditioner upon filling the tank up)
Nitrate = 0ppm
Nitrite = >7.5ppm
pH = 8.2ppm
Ammonia = 1.0ppm
Temp = 82-84F
Can anyone tell me what the recommended water parameters are for them to be healthy and happy and if these results i got should be of concern?
Thanks so much in advance for your replies!
Darren