How many 3 inch fish in a 75 gallon tank?

norfolkgarden · Nov 4, 2017

How many 3 inch fish can I fit in a 75 gallon tank safely.
3 inches will be the mature size.

This is disregarding any obvious concerns about compatibility which will be taken into account.

Tank is 75 gallons.
200 pounds of live rock,
No sump, just 2 MarineLand HOB filters with phox X
10 gallon water changes weekly. This amount can be increased if necessary for fish health.

Soft corals including
neon green kenya tree
20 different mushrooms
Corky finger
Some nicer gorgonians
Grandis paly's
Various sponges

Thank you

Maritimer · Nov 4, 2017

I'm not sure that number exists . . .

You've certainly got plenty of room for biofiltration, perhaps less for open-water swimming. Test your water often, watch parameters - especially nutrient levels. Keep an eye open for stressful social interaction with your finned crew. Your tank can offer clues as to when it's getting crowded in there.

What's "a bit tight" in one tank may be dangerous in another - each tank is going to be a bit different that way.

Yours, by the way, looks pretty awesome!

~Bruce

NeuroticAquatics · Nov 4, 2017

The size won’t matter as much as the types of fish. I’ve always gone with the idea that you are overstocked when your filtration can’t keep up with keeping parameters in check, so it will be different from system to system based on fish, filtration, feeding, etc.

What types of fish are you considering?

norfolkgarden · Nov 4, 2017

Thanks! It has been fun putting it together over time.

As far as the fish go,
um, kind of there already numbers-wise.

Over a year in the tank...

Strawberry dottyback,
Bicolor dottyback,
Diadema dottyback,

1.25 inch Black ocellaris clownfish,
.75 inch Orange ocellaris clownfish

1.5 inch six line wrasse
1.5 inch flame angelfish
Three 1.5 inch Banghai cardinals

1.75 inch flame hawkfish
2 inch longnose hawkfish
.75 inch pixie hawkfish (mostly cryptic)

2 neon blue cleaner gobies
2 neon gold cleaner gobies

Skunk cleaner shrimp
Blood red fire shrimp

8 assorted serpent starfish

6 turbo snails
5 astrea snails

6 blue leg hermit crabs
6 dwarf zebra hermit crabs
3 Scarlet hermit crabs

Just added 4 days ago...

4 Allen damsels from LiveAquaria, all under 1 inch

I was debating whether or not I could add 3 or 4 more Allen damsels and wanted to do it sooner rather than later. [emoji17]

norfolkgarden · Nov 23, 2017

Update 11-23-2017

All 4 of the Allen damsels died over a month long period.
They were supposed to be less aggressive than their larger cousins but were just as hateful as blue devils.

For me the answer to how many 3 inch fish can I fit in a 75 gallon tank is no more than 15 fish, with 7 to 10 of those fish topping out closer to 2.5 inches and the rest no more than 4.5 inches.

I completely overreached with the 4 damsels.

Once all of the fish listed mentioned earlier grow out, I will need to remove at least one of the Banghai Cardinals.
From what I've recently read about their behavior, it may end up being down to 2 without my choosing it.

Webslinger · Nov 23, 2017

I have 2 clowns, tomini tang, flame angel, long nose hawkfish, bangii carninal, coris wrasse, mandarin, diamond goby and dwarf morey eel. with no issues. Depends on filtration and amount of live rock and tank maturity. No comment from the tang police please. He's fat happy and healthy.