How Many is Too Many?

Hugh Mann · Mar 5, 2020

New to aquariums, and am just wondering how many fish can be put in a single tank without overcrowding/overwhelming the filter capacity. I know it's going to vary hugely based on what kind of fish, tank size, filtering and whatnot, so here's my setup.

FOWLR, 55 gallon tank, aquaclear 110, 40lbs crushed Coral substrate, 85lbs or so of live rock, two Mars Aqua 165w lights, and I just set up an aquaclear 70 as a DIY refugium with Dragons Breath as the macro.

About a month ago I added a Marine Betta, dwarf fuzzy lionfish, and a Greyfaced moray. Just on Tuesday I added a smaller lemonpeel angel, Tomini tang, flame hawkfish and a cleaner wrasse. A half dozen blue eyes hermits as a rudimentary CUC.

Everything is getting along and eating more or less fine, though the angel occasionally tries to evict the eel from its cave. I made sure that the newcomers are too big to get eaten, though that doesn't stop the lion from occasionally stalking the flame Hawk.

I would like to in the future pair up the tang and maybe the hawkfish, possibly a few other fish, but I don't want to overcrowd the tank. I do have plans to upgrade in the future to a 125 or larger, but the timeframe on that is unknown.

Flippers4pups · Mar 5, 2020

Hugh Mann said:
New to aquariums, and am just wondering how many fish can be put in a single tank without overcrowding/overwhelming the filter capacity. I know it's going to vary hugely based on what kind of fish, tank size, filtering and whatnot, so here's my setup.

FOWLR, 55 gallon tank, aquaclear 110, 40lbs crushed Coral substrate, 85lbs or so of live rock, two Mars Aqua 165w lights, and I just set up an aquaclear 70 as a DIY refugium with Dragons Breath as the macro.

About a month ago I added a Marine Betta, dwarf fuzzy lionfish, and a Greyfaced moray. Just on Tuesday I added a smaller lemonpeel angel, Tomini tang, flame hawkfish and a cleaner wrasse. A half dozen blue eyes hermits as a rudimentary CUC.

Everything is getting along and eating more or less fine, though the angel occasionally tries to evict the eel from its cave. I made sure that the newcomers are too big to get eaten, though that doesn't stop the lion from occasionally stalking the flame Hawk.

I would like to in the future pair up the tang and maybe the hawkfish, possibly a few other fish, but I don't want to overcrowd the tank. I do have plans to upgrade in the future to a 125 or larger, but the timeframe on that is unknown.

I'd say with a new tank and it's size, your maxed out now. I would recommend not adding anything else.

lapin · Mar 5, 2020

Its not the filter thats going to be a problem. Its going to be fighting to the death that will kill the fish

Flippers4pups · Mar 5, 2020

lapin said:
Its not the filter thats going to be a problem. Its going to be fighting to the death that will kill the fish

Yes that too. The Betta, lion and eel will be big problems for the smaller fish, quickly. They will out grow the tank fast. Respectfully.

ReeferSteve · Mar 5, 2020

Flippers4pups said:
Yes that too. The Betta, lion and eel will be big problems for the smaller fish, quickly. They will out grow the tank fast. Respectfully.

Absolutely this.

rastareefs · Mar 5, 2020

Looks like you have about 50" of fish so I assume you went with the 1"/gallon rule for stocking. Your filter is rated for twice the size of the tank which is good so I would make sure you feed heavy enough to keep the aggression low. Some of the fish will need bigger than a 55 gallon tank when they mature so that 125gallons upgrade will be a good thing for them.

Hugh Mann · Mar 5, 2020

rastareefs said:
Looks like you have about 50" of fish so I assume you went with the 1"/gallon rule for stocking. Your filter is rated for twice the size of the tank which is good so I would make sure you feed heavy enough to keep the aggression low. Some of the fish will need bigger than a 55 gallon tank when they mature so that 125gallons upgrade will be a good thing for them.

That's what was recommended to me, and right now with their combined size is maybe 30. I started feeding twice daily, a bit in the morning and a bit at night. Mysis, brine, chunks of shrimp, squid, scallop and clam. Seaweed and flake too. Plenty of algae for the angel and tang to graze on too. Haven't had any seriously hostile encounters that I've seen.

Hugh Mann · Mar 5, 2020

Flippers4pups said:
Yes that too. The Betta, lion and eel will be big problems for the smaller fish, quickly. They will out grow the tank fast. Respectfully.

Yup, that they will. So far they seem to be mostly leaving the new fish alone, though I have caught the lion eyeing up the Hawk a couple times. Pretty sure the Hawk is a bit too big to be swallowed. For now.

You say they will outgrow the tank fast, how fast? Weeks, months, a year? I haven't come across too much material regarding the growth rate of these fish, just their typical mature sizes.