My tank has been up and running for several months now, and seems to be doing well. (aside from a minor outbreak of caulerpa... curse my curiosity for letting that one tiny piece grow at first) Current residents are 5 hermits, 3 nassarius snails, a falco hawkfish, and a starry blenny. The hawk is such a fun little guy to watch, and the two get along well. (blenny is quite quirky and fun to watch too) I supplement nori a couple times a week for the blenny, since he does seem to be eating algae around the tank, but that was not my main reason for getting him. Lately, I've been debating adding one more fish to the mix, and that would be a rusty angel.

Based on what I've read from lgreen's stocking thread, and a couple other random sites across the net, 20g+ is required. Given that I'm running a 26g w/ AC 130 fuge (packed with chaeto) and doing a 5g water change every 4-5 days, do you feel it would be too much to add a rusty angel? I like the way they look, would be great to have an open-water fish, (other two are always perched, except at feeding time for the hawk) and it would also pick at the rock a bit and take care of small bits of algae. (still debating an emerald crab too... though I'm weighing the pros/cons on that still)

Are there any other fish I should look into with similar colors and habit that might be better suited to this size tank? I rather like bangaii cardinals also, and I might go with something like that instead, but I'm currently interested in the angel.

It is on the small side - they can get what 4" or a little more in length? Try a pygmy angel - they max out about 2-2.5". Other benefit is they are very, very hardy!

I had a coral beauty angel. They poop A LOT, but I don't know if a rusty is the same. I moved mine out last weekend because he had ich (and subsequently died) and the rate of my nitrate accumulation dropped in half when he left that tank... If I were to get another angel (which I would) I would probably only drop it in a tank with a skimmer on it. The AC fuge doesn't do nearly as good a job. I do 5g wc's every weekend on that tank (20 gallon hex, about 16g actual water volume).

Thank you for your insight. I had suspected that the Rusty was going to be a bit on the large side at 4", but having read about keeping one in a 20g perked my interest. Perhaps I'll forego the angel route... we shall see. (mostly contingent on whether a flameback angel would be a viable option)

I currently am not running a skimmer, though I have toyed with the idea of running one. I've often considered the Tunze 9002, as I've read several good things about it, but I've also looked at the possibility of a Prizm skimmer. Anyone have any experience with these? I haven't done any research thus far on them, just thought the design looked fascinating.

As I know most folks like to see numbers, I decided to do a full battery of tests tonight.

Temp - 79.3F
SG - 1.025
Calcium - 440
dKH - 8 (probably more like 7.5, but the solution didn't turn fully yellow until the 8th drop)
Phosphate - 0.0
pH - 8.4
Ammonia - 0.0
Nitrite - 0.0
Nitrate - 0.0
Mg - 1320

I know the 0 Nitrates seems a bit weird, I was a tad skeptical as well. This AC 110 is literally packed with Chaeto, on a 12 hour light cycle. (runs from 4am - 4pm, mostly because having that light come on when the actinics go off makes it much harder to get to sleep) I've also got quite a bit of caulerpa growing in the tank. I feed the tank twice a week (usually 2/3 - 1 cube of frozen mysis, occasionally blood worms or brine shrimp) and I am very particular about how I feed... I spend probably 15-20 mins with a long pair of tongs feeding individual acans and duncans, trying to offer each hermit a mysis shrimp, feeding the nassarius snails, making sure the plate coral gets its share, etc. I also add phytoplankton once a week. (and in case it comes into question, yes, I did cycle the tank, yes, I have seen ammonia, nitrite, and nitrate along the way) I'll test the nitrate again a few times this week to see what comes up. (and I'll test using both nitrate kits, just to see if I get any difference)

At any rate, while I'm somewhat disappointed that the rusty angel is off-limits, I really do not want to over-load the tank. I do intend to keep more to corals than other inhabitants anyway. (and I'll post some photos in the near future, just for the heck of it)

Nothing is off-limits. It's your tank and you know how it reacts and what it can handle. Unless you are worried about karmic consequences or unwilling to gamble the $$$, get the fish and see how it goes!