Oh dear. I agree with many of the posts here, the tank should be cycled first and a dechlorinator like AquaPlus is also a wonderful thing to have, also the temperature of the water needs to be correct so a thermometer is also a must have (tropical fish need temperatures around 70 to 80 degrees usually). I hope you have a good filter as well, something like Aqua Clear would be good to begin with. Also, a fighting fish is not really a community fish usually and you mentioned an african something you weren't sure of, if it is an african cichlid a 10 gallon may not be suitable for this fish and usually they are more aggressive and harder to take care of for a beginner. And if your fish died on the the transport home, that is a usually a bad sign on the part of the pet store (who gave you bad advice to begin with) either with sickness or if the travel back home was long the fish may not have gotten enough oxygen. For now since you have the fish and don't have an extra tank I would get something like Cycle to help the fish a bit and maybe return the african cichlid if that is what it is. You'll need to get other things eventually such as a heater when it gets colder and a gravel cleaner. There's a lot of information on the internet as well as many books at your library or book store available to you and it does help a lot =) Let us know how the tank is doing
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