For newbs coming to the forums asking why all there fish died and when asked if they cycled there tank they ask what does that mean. Not researching fish before you buy them. Taking petstore employees advice (not saying all petstore employees don't know what there talking about but a lot don't especially chain stores). For me bringing my 150 gallon home that I bought off craigslist filling it up almost all the way only to find out that the stand is not level then having to empty the tank to shim the stand.
I get over excited when I have room for another fish, but instead of just replacing one, I start stockpiling... bad, bad!!!! <--- that's me scolding myself..
same,
about 6 years ago i got red and brown 'natural' gravel at petco.
recently i tried to re-use it and noticed a plastic coating was coming off and it wasn't natural nor was it gravel at all.
then you'd think i'd learn from my mistakes, but i bought this beautiful blue gravel at petsmart. i thought it was dyed gravel basically. well turns out it wasn't gravel, it was plaster with some kind of paint on it, after rinsing it and putting it in my tank, it looked horrible. tons of white spots showing where the paint had totally come off.
never again, i'm only buying caribsea products, play sand, or landscaping gravel from the home improvement store
I remember getting a 10gal tank when I was younger and getting goldfish to put in it. I filled it up and put the fish in not knowing about cycling or even chlorine in the water needless to say the goldfish died and I gave up ever keeping fish till lately when I got some turtles that I now keep with minnows and a couple comets successfully =D. We all learn from our mistakes
Now I'm hoping to soon buy a 75 and get some cichlids.... maybe I shouldn't have learned how to keep fish I'd have more money in the end lol