doing stupid things like:
I need snails for my puffer, I'll just dump a few in my community tank and I'll breed them there, woops now that is a LOT of snails
or
lets kill the snails by dumping all the plants into scorching hot water, the plants didnt really apreciate it
or
lets go with more filteration a fluval 4 should do the trick in my 20 gallon NOT
or
and popular by demand:
funny the hood didnt come with light bulbs, well these 25 watt bulbs I use for the bathroom will do the trick, (what is that smell)
finally I'm guilty of forgetting to unplug the heater before changing the water,
(ZAP, what the , ZAP ouch, ZAP oh crap the heater, *sizzling sound* ouch, oh yea its hot.)
*Note*
Black Beauty is not suitable for aquariums
Sand does not work well with Penguin Biowheel powerfilters
Gauramis dont handle stress very well
Neons dont do well with any additives or preservitives
Male Dwarf Puffers can be intolorant of there own kind even if it a female
Medications can actually make the situation worse