Question about my dying fish and cycling

[Breakthecycle2]

About a week ago, I lost 15 fish in a 4-5 day span. I bought some fish a few days prior from a store I shouldnt of. All those fish died and took with them 2 regular neons and 5 black neons. The fish i bought and died within a few days were, 2 blue rams, 3 more regular neons and 2 cories. I also lost a corie I had for about 2 weeks. Now one of my bolivian rams is breathing heavy, which was the only visible sign of distress. I will probbaly lose her too. My question is, besides the fish i bough that one day, most of my fish were added within the first week I started my tank. Is it possible that the cycling finally took its toll and thats why my bolivian is now dying?

 

[Bloo]

I think it's a good idea to give a little more info about the setup of your 20 gallon tank and how it's been over the past few weeks - if you want a more accurate guesstimate. I know from reading some of your treads over in the Emergency section, that you have an 8 week old tank and two weeks ago you replaced the filter - and within that time you had 18 fish (neons, rams and cories) at one time in that tank. Of which you've lost the vast majority after putting in the latest batch of fish.
During that time you treated the tank with coppersafe (even though fish had no actual signs of any illness apart from laboured breathing). But you subsequently thought they had some bacterial infection ?

Have you treated them for any possible bacterial infection ?

 

[Breakthecycle2]

It was a little less then 18 but yeah. My filter is about 3 weeks now or maybe even a month old. Ammonia and Nitrite are 0 and PH is 7.6. Temp set at 79F. I did treat the water with Copperdafe because a member recommended I do so. I have not treated for bacterial infection because I don't even know what to treat for.

 

[Tokis-Phoenix]

how many fish do you currently have in the tank? i would not buy any more fish at all until your cycling process is finished, and that could take some months, you should also thoroughly research any fish before you buy them as buying fish on the spur of the moment so to speak, is one of the most common ways people end up with agressive or tank busting fish. Also, even for a mature tank you should never add more than 2-3fish a week unless they are 1inch or smaller- your filter bacteria has to adjust to the bioload.
A 20gal tank is a small tank and due to that you cannot have many fish in it wether its cycled or not so do not expect too much of your tank either, i wouldn't have anything that grows bigger than 4inchs in a 20gal personally.