Keeping angels can be a lot of fun and will bring years of enjoyment with proper care and balanced diet.

Tank Size
You will need to decide how many angels you would like to have before determining what size tank they should live in. Keep in mind they grow quite large and require plenty of space to grow properly.
Example: Nickel sized body-1 fish per gallon of water
Quarter sized body-1 fish per 2 gallon of water
Silver-dollar sized body-1 fish per 3 gallons of water
Lg. Size for pairing- 1 fish per 5 gallons of water
Breeding Pair- 20 or 29 gallon tall

Filtration
Angelfish prefer gentle movement in their environment. I use either Sponge filtration(smaller angels I am growing out), Power Filters(that have flow regulation), Under gravel filters also work well. I recommend changing filter pads or cleaning sponges on a regular basis along with ample water changes, the more fish you have in the tank the more frequent you should change water. Change at least 50% of water when doing a water change. You can not change water to frequent but not doing at all could result in problems in your tank.Depending on size of tank and amount of fish present I would change anywhere from once a week - every 2 or 3 weeks depending on load of fish and how good of filtration is in operation.

Temperature
Angelfish can withstand different temperatures. Immune systems tend to be stronger at a higher temperature.
Upper 70's works well for a show tank, as 80-82 works better for breeding. Angelfish will live longer at a lower temperature while at a higher one such as 80-82, they will grow faster, and eat more food more often. They will also be more apt to breed more frequent and will have a better immune system. Higher temperatures will also lesson their life span a bit.

Feedings
Angelfish love to eat. Be very careful not to overfeed them. They like to eat a wide variety of foods such as several types of flakes, mine love dehydrated brine shrimp and dehydrated bloodworms, both of these also come in frozen. The key is to watch what they eat if any left over after a few mines, I would say you have fed too much. Next time feed a bit less. I feed my Angels 3-4 times a day. Flakes, dehydrated shrimp, dehydrated bloodworms, and occasionally frozen brine as a treat. Making sure not to feed to much my rule is less more often and then food gets eaten= not having a role in causing bacteria to grow in the tank.
If you are having a health issue with any of your fish you may email me if I can help you I will try, and I would also highly recommend you see my favorite links there are several good sites in which you may find your answers.
As I am not a doctor just an angelfish hobbyist/breeder.

There are a few items you will need to have on hand,

1. variety of food
2. good declorinater such as, prime, stress coat, start right, basically depends on your water conditions where you live as to what you may need. I use prime.
3. Ph and Ammonia test kit
4. may need ph up or down depending on what yours reads. Angels can live in a wide variety of ph ranging from 6.8-8.2 I keep mine in neutral zone around 7.
5. I also use black water conditioners in only my show tanks , Instant Amazon, and Ketapang Vital. Since I have been using these I can see much more vibrant colors so I figure it can't hurt I highly recommend it I do not use on my juveniles at this time. Only in show tanks or in the breeders tanks.
6. few medications may come in handy. Here are a few you may consider in case of an emergency. Methlyne Blue,You will need this if breeding for the hatching jars and also if having a fungus issue.
Acriflavin+ helps if having a fungus problem
Quick Cure in case of ich
oxytetracycline( antibiotic )in case of bacteria

I also keep a few medicated flakes on hand such as:Metro flake, and oxy flake, The first helps in case of Hexmita, the second has oxytetracycline in it so if needing antibiotic and fish are still eating is good to have on hand! Both are available threw

www.4fishstuff.com.

www.nationalfishpharm.com

Before using any medication in your tanks if you are not sure of what your problem is you should consult with some one who may be able to help you. There are several sites in my favorite links that can be of assistance. Once again I stress I am not a Doctor, but there may be times your fish could be sick and you may not have direct access in getting meds in time so its best to be prepared.

I hope this information can be of help to you I have tried to include as much as I can that helped me.