You can save some money on the filter by going for a hang on back (hob) instead of a canister. I love aquaclear70 , had one running for six years now with no trouble . Canister filters are more advanced and a lot of people prefer them, but for a 40 gallon I don't think its neccesary. Spend the money yousave on plants or decor such as driftwood or rocks. I think the stocking list suggested by thekoimaiden is excellent advice, and you can alter it as far as exact species of gourami, danio... . Its hard to say how many gouramis will get along in a 40 because there is a lot of variation within each species ; some fish are very aggressive, some are extremley shy and skittish. I have 2 dwarf gouramis and a blue gourami in a 29 gal and they get along fine. Try to get young fish if you can. Lots of plants and blind spots / hiding places will help your fish coexist more peacfully, they won't be in eachothers sight so much as in a bare tank. I can't stand aggression in my tanks. I thinks its a wonderful present to give to your dad, I wish I would get a new tank for xmass from my kids! Best of luck to you.
P.S. playsand works great for fishtanks but the ordeal of rinsing it is long and labor intensive. I just changed a tank from gravel to sand, the results are wonderful but if I had it to do over I would spend the money on good fishtank sand. Still has to be rinsed, but a lot less than playsand. Its expensive in the fish store but I took 8 total hours of work to rinse a 50# bag and ended up with about 30# of sand after all the gunk was washed out. Still its another way to save some $$$ and its completly safe for your fish.
Aquarium water clarifier will settle the particulates out of your water if its a little cloudy from the sand. Once its settled you shouldn't have any cloudiness unless you really stir up the sand, which I would advize not to do. Thanks and good luck!
Last edited by rsskylight04; 12-03-2013 at 12:51 PM..