Banana plants are ok in an aquarium with proper care.

Banana Plant Aquarium Husbandry, General Care and Feeding
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Despite its exotic appearance, the Banana Plant doesn’t require any specialist care, and simply adding a good quality general aquarium fertilizer to the tank will take care of the plant’s nutritional requirements.
Banana Plant Basic Care Nymphoides Aquatica - World News
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The second and third picture are from 3 days ago. Sorry about the lighting in the third one. The leaves started turning dark green and kind of transclucent, and the edges began curling under a little. They also developed holes that have a brown edge and yellow around them. Are there any diseases that commonly affect these guys? I tried googling it but most search results I get are about actual banana plants (as in the fruit), and the few that are about the aquarium plant don't talk about diseases, just basic care info. Although I think I read somewhere that plants in this family are more sensitive to potassium deficiency but I might be getting that mixed up lol... I've been googling aquarium ferts and looking at those deficiency charts/guides and I'm a little confused. I could use some help narrowing things down and figuring out if I'm dealing with nutrient deficiency. Any help will be greatly appreciated! This video explains some basic care needed to grow a banana plant in your home aquarium. The banana plant is a beginner plant with big yellow/green leaves.
Photo provided by FlickrI'd never even heard of an aquatic banana plant before so I figured it best to search how to care for it. What I read was what I was doing.
Photo provided by FlickrI don't think it's my care or aquarium as the other banana plant is completely fine and never shows any sign of rot. It must be this specimen.
Photo provided by Flickr
Care: Nymphoides aquatica is really easy to take care of and lives in most conditions, being tolerant of deep water and low light. This plant can be grown rooted or as a floating plant and can produce floating or submersed leaves. Low light or shaded conditions and colder weather will result in plants reaching maturity in submersion. 80% of Nymphoides aquatica plants will sink to the bottom and root themselves. Left to float to the surface, the banana-shaped tubers will turn into obvious lilies fast.
The floating Nymphoides aquatica‘s leaves typically mature, reaching full growth, in one to two weeks, dependent upon conditions and other environmental factors and flowers develop from just below the leaf structures. Given optimal conditions, this plant will commonly flower in the tank.
Although Nymphoides aquatica is a perennial plant, returning years after year when cultivated in water gardens, some recommend replacing plants every four to five years for optimal showing.Banana plants are Rosette plants. They are the only members of this group that grow in aquariums because of their hardiness. The banana plant is a perennial. Aquatic banana plants are aquarium plants that need a moderate amount of care. When you get the banana plant, check for any broken leaves and remove them. When removing the leaf, remove part of the stem. This plant cannot heal broken leaves. This plant can reproduce asexually by pressing one of its leaves into the substrate and leaving that leaf behind, creating a separate plant. They create new plants every four to five days.Aquarium plants such as the banana plant can remove fish waste and can increase the oxygen content of the aquarium for free. Many aquarium owners get banana plants because they like the unique shapes of the banana-shaped roots and the heart-shaped leaves. These plants are not difficult to take care of and do not have high lighting or nutrient demands. When adding the plants to the aquarium, be careful because they are more fragile than terrestrial plants.A few days later I noticed the banana plant was starting to get a little dark and mushy. I'd never even heard of an aquatic banana plant before so I figured it best to search how to care for it. What I read was what I was doing. I had the option to bury most of it or let it float around, I chose free floating but saw it dried on top, and placed it under a small curl in the tank divider so it's submerged.