Suggestions for a 72 gal. fish only

[Uncarved Block]

I've recently started a 72 gal. marine aquarium, and am planning for it to be a fish-only setup. I already have about 35 lbs. of uncured live rock in the tank, but no fish yet. Are there any suggestions about what would be good fish for tank of this volume?

Also, how long should I wait before putting fish in? I've heard that adding hardier species early on is inhumane due to the waves of nitrates and amonia, but I've also heard that it is good to cycle with fish in the tank (since their waste output feeds the bacteria on the live rock).

 

[Max]

The waste from your curing live rock should be more than sufficient for a cycle. The first thing I would do is buy a test kit so that you have an idea of what your parameters are and how far you have to go in your cycle. I would make it a point to test every few days until you get a good feel for the tank,"maybe more often in cycle." Try to keep your ammonia under 1 ppm so as to avoid killing off large numbers of inverts on your live rock," if you have a crushed coral substrate I'd strongly urge you to rid yourself of it."
I'd never use fish in a cycle on purpose ,"sometimes you'll get a mini-cycle if you add too much at once or if a fish proves to be more active than what you planned."
As an alternant if you don't reach somewhere around 1 ppm for ammonia you can add a cocktail shrimp and let it be your ammonia source if you don't feel that you've reached the desired levels. In a fish only with no inverts or obligate feeders you might even consider stressing to 1.5 ppm but, I've always done well with 1.0. Then stock your tank fairly slowly to make sure that you have enough bacteria.
hth
chris
WELCOME TO AC!!!

 

[Uncarved Block]

Thanks for help. Its been five days since I've added the live rock, and the nitrate and amonia levels are both at 0 ppm (the amonia might be a little higher: from 0 to 0.25, its hard to tell). Does this mean the cycle still needs to get started?

 

[Max]

Maybe, did you ever have any readings on your test kit?

 

[Uncarved Block]

No, that was the first time I used it.

 

[Max]

Was your live rock cured? If it was I'd dose my tank to .08 ppm and do a reading the next day and see if the level is reduced. If it wasn't cured it may not have had enough time yet. I wouldn't add anything until I was 110% sure that it was cured as long as you keep your ammonia levels below .1 ppm it's not toxic and won't hurt any of life on your l.r.

 

[Uncarved Block]

My l.r. wasn't cured when I bought it. I did another test today, and its still at zero for both ammonia and nitrates. It seems that there's a lot of growth on the live rock though - it's now covered in what looks to be red algae, and some green algae. Would that mean die-off has finished happening? Is a lot of red algae on the rock a good or a bad sign?

 

[Max]

I don't think that it's very likely to be honest. I'd stress the tank with a little pure ammonia or like a shrimp or a shrimp sized chunk of fish to make sure you're cycled.
hth
chris

 

[Uncarved Block]

Thanks for the advice! Down the road, would a sailfin tang be okay in the aquarium?

 

[dorkfish]

Thanks for the advice! Down the road, would a sailfin tang be okay in the aquarium?

I personally wouldn't do it, nor would I recomend it, as sailfin tags can hit 18" and all tangs need a lot of swimming room.