Managing Aggressive Aquarium Fish

Choose compatible fish!

It is lovely and relaxing to have a peaceful, well-balanced aquarium. When your fish are well-matched and get along, it is a delight to sit and watch them peacefully interact. However, if you have one or more aggressive fish, you may end up witnessing more mayhem than peace. Aggressive fish can be very mean and destructive and can really ruin your enjoyment of your tank, not to mention making life miserable (or non-existent) for the other fish in the tank.

The first rule to follow to avoid aggression in your tank is to do your homework. Take a trip to your local fish store and look at the various types of fish, but don‘t buy any yet. Take a notebook with you, and write down the names of the types you like. Talk with the staff about which fish go well together and how they behave, but take their advice with a grain of salt! Many times, the young folks who work in pet shops don‘t actually know what they are talking about. They are well-intentioned, but they may very well send you home with a terrible, incompatible mix of fish that will end up killing each other in fairly short order.

If you must buy something at the pet store, buy a good book on different types of fish and fish care. Or take your list of fish that you like to the library or do your research online. Check into eating and sleeping habits, level of aggression, and speed and extent of growth. A few guppies may be alright with a baby Pacu, for example, temporarily, but it won’t be long until that Pacu is the size of a dinner plate, and your guppies will be no more. Additionally, you will probably be looking for a newer and bigger aquarium or someone who is willing to take on a very big, aggressive fish.

When selecting fish to avoid aggression, it is helpful to group by type. For example, you could have an all cold-water tank with goldfish and corydoras (small cold-water catfish). Even then, you will want to have similar types of goldfish. Comets can wreak havoc with moors, fancy bubble-eyed and lion head types because they like to pick on their bizarre physical features. So if you are going to have plain comet goldfish, stick to that. If you are going to have fancy goldfish, stick to that. Don’t mix tropicals with cold water fish. Tropicals tend to be more aggressive and will probably end up picking on your goldfish, no matter what kind they are. Additionally, you will run into problems with temperature, salt levels, and so on.

Live-bearing platys combine well with other live-bearers and many bottom feeders.

Title: Fish ~License: sxu license ~Photographer: hagit:
Title: Fish ~License: sxu license ~Photographer: hagit:

With tropicals, selecting fish of a type will help prevent aggression.

Select all live-bearers: guppies, platys and mollies. Be careful not to select mollies or platys that are going to get huge, if you want to have guppies. All tetras is also a good choice. They are similar in needs but vary in color and appearance to make a nice, interesting tank. Keep your fish all of a size. Almost any kind of small bottom feeder will do well with live bearers or tetras, but understand that loaches will gobble up your babies pretty quickly.

Select all barbs if you want to have a tank of semi-aggressive fish. They come in a variety of colors and types, but they all get along with each other pretty well (but with other fish, not at all!) They are schooling fish, like to be in big groups, and are all pretty fast . If you have all barbs and a Chinese algae eater or a loach as your bottom feeder, you should have a fairly well balanced tank.

Don’t get too many bottom feeders. They tend to be territorial. Don’t mix loaches. They will kill each other. One loach to a tank is plenty!

Goldfish, live-bearers, and barbs are good choices for beginning aquarists who want a community tank. Not all fish are schooling fish. Some fish, like Gouramis, Betas, fresh water puffers, and some of the larger, challenging fish like Oscars are simply better off alone. A single Gourami, Beta, or Puffer in a small (at least three gallon) desktop tank makes a nice pet for a beginner. I don’t recommend mixing them with any other fish, or you are likely to have problems. Save the challenging fish for when you have gotten a lot of experience under your belt. Once you have learned what is really involved in aquarium care, you may decide against very challenging fish altogether.

Copyright: SuzanneBennett: June 5, 2009

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visionandfocus profile image

visionandfocus 5 years ago from North York, Canada

Wow, this is really useful and fascinating! My dad used to buy fish that kept eating up others already in the tank. Now I realise he shouldn't have listened to the store owner and done his own research. This is a great resource for an existing and even a potential aquarium owner (like myself). Thanks for sharing! Voted useful and up!

justmesuzanne profile image

justmesuzanne 5 years ago from Texas Author

Thanks! I'm glad you found the article helpful! :)

JayeWisdom profile image

JayeWisdom 5 years ago from Deep South, USA

This is a wonderful hub for people who may be contemplating an aquarium. Although I don't anticipate getting my own aquarium, I enjoy looking at fish in others' tanks. Even looking at your hub photo made my blood pressure go down a point or two!


justmesuzanne profile image

justmesuzanne 5 years ago from Texas Author

Thanks! Glad to be helpful! :)

Lyn.Stewart profile image

Lyn.Stewart 5 years ago from Auckland, New Zealand

I hope anyone who wishes to get tropical fish finds this hub. I knew some of this info though you have definately taught me alot more so thank you for that.

I must admit to only having owned cold water fish (various types) and axalotals myself ... I now prefer fish ponds personally.

Isn't there a fighting fish that you can only have one male in the tank or they fight to the death as well?

justmesuzanne profile image

justmesuzanne 5 years ago from Texas Author

Yes, Siamese fighting fish or Bettas are like that. So are gouramis, which are closely related. You can't have them with each other or with bettas. There are some bettas you can keep in a community tank, but it's hit and miss. It's better to keep them alone. They're happier that way, anyway.

Lyn.Stewart profile image

Lyn.Stewart 5 years ago from Auckland, New Zealand

wow I wasnt aware there were so many you had to keep seperated ... thanks for that I love learning new info. You never know when it will come in handy.

justmesuzanne profile image

justmesuzanne 5 years ago from Texas Author

Oh, there are more than that! :)

Max A Pooch profile image

Max A Pooch 5 years ago from Illinois

i use to have tropical fish and became an advid hobbyist with six tanks ranging from 80 gallons down to 20 gallons. I wish I had known what you shared in this hub when I first started out. Good stuff!

justmesuzanne profile image

justmesuzanne 5 years ago from Texas Author

Thanks! Yes, it's easy to get addicted. I had 30 bettas at one time. I also had 17 aquariums! Now I just have a pond! :D

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