Hi I am new to my hobby I just got a 25gal aquarium and filled it out with freshwater tropical fish and as a nub started with fish that is more tolerable to harsh conditions like Platys, Hi-fin tetras, neon tetras, glow fish I had one nub but unfortunately he died about two days ago. I also have 1 eel that looks like he has ick and I am concerned about his life and my whole tank to be honest. I have this tank for about two months already and the last testings on the water condition (from yesterday) showed that I have really high level of nitrites - 10.0ppm, nitrates - 40ppm, water hardness - 75GH ppm, alkalinity - 80KH ppm and PH - 6.8 if this is going to help some. I just did a 35% water change and conditioned it and added some aquarium salt for freshwater. So please tell me what I am doing wrong?
Thank You!

It doesn't sound like you are doing anything wrong.
An aquarium takes time to cycle (develop the nitrogen cycle).
If your fish appear to be ill, treating them with medication may be necessary.
Continue doing partial water changes, I'd recommend 15% daily until your aquarium is fully cycled.
You will be able to tell when the cycle is complete when you have a 0ppm nitrite reading and a 0ppm ammonia reading.
Please read this sticky note at this link for a better explanation of the aquarium cycle/nitrogen cycle.
Once your aquarium is cycled much care must be taken not to clean away the good bacteria. Your filter should have come with some sort of bio media for the good bacteria to live in.
This media should not be cleaned.
If you have any questions, I'm hear to help.
If your not sure what the bio media inside your filter is, you can give me the make and model and I'll find it out for you.

Thank you so much for your quick response Kae and about the bio filter I know exactly where it is and I didn't touch it at all and really don't intend to (:

Great! Your tank should be fully cycled soon and you'll be able to enjoy your new hobby.
If I can help you with anything in the future, just let me know.

AKaeTrue... I know it has been a long time since you posted on here but if you could give me some help I am having a similar problem. I have had the tank for 3 months now... I have a 30gal freshwater tank with danis, Nitrate filter, water changes daily with conditioning, temp stays between 80-82, feeding very small amounts once per day, yet I can not get the nitrites below 5. The quarium speciality shop suggested that a live plant would help control nitrite levels and help with the cycling but I am curious if there is any decorations that could make it worse, we have the neon decorations and black/neon rock mix with a statue and then there is a large clam shell(real) we found on the beach that is in the tank as well. Would any of these affect the nitrite levels, would a live plant help, and do you have any other suggestions of ways to get the nitrite/nitrate levels down?