National Aquarium planned to open later this year : Look: A new aquarium will launch in Abu Dhabi with 25 species of sharks and rays
In Czech! newspaper, I have just seen an article about this aquarium mentioned. Still under construction (64% built) and opening date "sometime next year". Article
Dubai is an other Emirate. If Dubai has an large aquarium, Abu Dhabi will get a larger one. Dubai has a large safari park, now Sharjah (another Emirate) will get an even bigger Safari park. So it's looks weird that they have so much aquariums, but it isn't really that weird.