i had brackish cichlids for my entire life. So colorful!!! At your lfs they should have rocks that have salt in them and release them, they help control salinity and provide shelter. Cichlids are the way to go. I dont no any ph, ammonia, nitrate lvls etc but if you get cichlids they need lots of rockwork. Easy to maintain. I used a HOB filter for 110 gallons on my 4 foot 55 gallon. You will need a siphon hose to clean the fish droppings from gravel. These work by hooking it to a hose and using hose water to create a siphon. It vacuums out the poo. It will probably suck up sand tho, so if u use sand i cant help you there. ON your HOB make sure you keep good carbon. I fed the fish once a day. Cichlids breed a lot and if hey have babies get them quick or they will get eaten!!! Put them in a separate tank or breeder tank, if you catch the mom pregnant then put in seperate tank and remover her after birth or she will eat them. Its hard to find a pregnant mother because they hid in the rock work when they are pregnant. Cichlids are your best bet. They are at every LFS, not too expensive, and their colors are phenomenal. Do not get albino ones tho, every LFS wanted me to buy them all the time and when i did they hardly ate, did not really swim, and died after a couple months. They arent that good looking anyway. I hope i was some help.