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Fish/Red-Finned Shark


I have had my Red-Finned Shark for two-weeks. She is in a ten gallon tank with three Marble Lyre-fin Mollies(two male, one female), two ghost shrimp, and two Bamboo Shrimp. About a week ago one of my bamboo shrimp died. I found out that my filter was too powerful for bamboo shrimp but not before the other died a few days later. Since then my Red-fin has been acting strange. She started swimming and floating around sideways at first. Now she has stopped eating and is showing the signs of oxygen starvation; however, none of the mollies are acting this way. My mollies and ghost shrimp seem to be fine. I have two lava sculptures, a large cave, three small live grass plants, and a small fern plant. My red-fin is obviously stressed due to her color fading to pale grey around her head and mid-body. What is the problem with my Red-fin and how can I make her better?

Hi Jasmine

Your tank is too small for a Red Fin Shark aka Rainbow Shark, it needs at least a 30 gallon tank. Your tank is also overcrowded. You also would need a 30 gallon tank for the current fish and shrimp you have. I would consider moving these fish into a larger tank or you will likely lose most of them.

To immediately help your Red Fin Shark, do a 30% water change and change the carbon in your filter. Do another 10% water change in a couple of days and test your water parameters. Then do 25% water changes weekly. You could also add an airstone if you don't currently have one. You MUST do 25% water changes every week. In this case where the tank is overcrowded, I would do 25% water changes on the weekend, then another 10% water change about mid week. Change the carbon in your filter once a month.

Here are a couple of links to help you with your Red fin Shark.

Please consider moving these fish into a larger tank so they will be happy and healthy. Hope this helps, good luck!



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Richard Hight


I own and maintain several freshwater aquariums from 2 to 180 gallon. I can answer most questions about freshwater aquariums, including setup, cycling, maintenance, compatible tank mates, feeding. Moving? I've moved fish both across town and across the country and can help you get your little aquatic friends to their new home safely. I know and have experience with most freshwater community fish, South American Cichlids and African Cichlids. I don't answer questions about Goldfish or keeping Goldfish with Tropical Fish. I also don't answer questions about keeping crustaceans (shrimp, snails, crabs etc) with Tropical Fish, nor questions about saltwater fish or aquariums. I'm not available to answer questions on weekends, this is when I do maintenance on my own tanks.


Many years of personal experience with fish and aquariums

HSG 2010-2011 prof

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