Calculation for # Fish

TwoShoesOrOne · 06/10/2019, 04:46 PM

I've seen a few rules of thumb about bio load (such as 1" of fish per gallon), etc.

I was wondering if you should use the total volume of the system (display and sump) or just display?

Thank you.

lpsouth1978 · 06/10/2019, 04:52 PM

This is a VERY general rule and will vary by fish. But to answer your question, I would use total system volume. Also it is 1" of fish (full grown) per gallon. Make sure you calculate based on the max size of each fish.

mcgyvr · 06/10/2019, 05:52 PM

And I'll answer its only display gallons and not total system gallons..

lpsouth1978 · 06/10/2019, 06:07 PM

And this is why it is a general rule. There is no single correct answer. Some tanks can handle more fish than others, a lot of things will influence how many fish your system can hold before becoming a problem.

Anemone · 06/10/2019, 06:42 PM

Quite frankly, it's a ridiculous rule, that fails to take into account inter- and intra-genus aggression, tank dimensions (a long tank isn't the same as a tall one) and type of fish (tell me an inch of dartfish equals an inch of tang)...

Kevin

Uncle99 · 06/10/2019, 07:00 PM

Quote:

Originally Posted by Anemone

Quite frankly, it's a ridiculous rule, that fails to take into account inter- and intra-genus aggression, tank dimensions (a long tank isn't the same as a tall one) and type of fish (tell me an inch of dartfish equals an inch of tang)...

Kevin

100% agree

Sk8r · 06/10/2019, 07:59 PM

The most common mistake people make in stocking (outside of not knowing aggression level, which is often a function of overcrowding and panic) ---is not realizing these fish are shipped at a 'shippable' size, ie, tiny. Our store has an ever-so-cute 1.5" rabbitfish. The kicker is, it gets 10" long real fast and is venomous to boot. It gets more and more freaky as it grows and lacks room. This fish attacks when spooked. So ---look at the adult size, and plan for that. Don't think you can trade a 10" rabbitfish back to the lfs. They can't accommodate him, and finding a fellow hobbyist that wants him is real hard.

j.falk · 06/10/2019, 08:15 PM

And with that being said rabbitfish sales plummeted to an all time record low.

TwoShoesOrOne · 06/10/2019, 09:08 PM

Okay, very simple rule of thumb is silly I agree. But if we are talking about bio load on the system I guess a good medium would be to consider a number based on being between the display and total display sump. So it might be
between 4 and 8.

I have a 25 gal displapy and 25 gal sump (filled to 15 gal) and 6
small fish which shouldn't grow too big I think
1-clown
2 damsels
2 spotted dominos
1 fire goby.

Thank you.

bshow24 · 06/10/2019, 09:17 PM

Bio load isn't necessarily based on the sump. It's based on how much area there is for beneficial bacteria to grow, which typically is live rock and sand in the display. Of course if the sump has a decent sized refugium or some filtration process to help the bacteria (siphorax comes to mind) then of course that can help with bio load.

I personally take this process as a 2-step thought. 1) How many fish can fit in my DT? Once I get this answer then 2) Can my bacteria handle that?

Anemone · 06/10/2019, 10:26 PM

Quote:

Originally Posted by TwoShoesOrOne

Okay, very simple rule of thumb is silly I agree. But if we are talking about bio load on the system I guess a good medium would be to consider a number based on being between the display and total display sump. So it might be
between 4 and 8.

I have a 25 gal displapy and 25 gal sump (filled to 15 gal) and 6
small fish which shouldn't grow too big I think
1-clown
2 damsels
2 spotted dominos
1 fire goby.

Thank you.

Four damsels and a clown in a 25 gallon tank may be pushing it. You don't say what type of clown, or what type of other damsels you have, but Dominos have a maximum size of 5", and can easily grow to 3+ inches. Depending upon the type of clown, it could also grow to 4+ inches.

Beyond the size issues, you could also have significant aggression. The bigger most damsels get, the nastier they get, and many damsels don't like other damsels. Clowns also get more aggressive as the age/grow too (they're damselfish as well!).

Good luck!

Kevin

j.falk · 06/11/2019, 03:55 AM

Dominos can get very aggressive as they get bigger. I know that from personal experience.

TwoShoesOrOne · 06/11/2019, 09:02 AM

Quote:

Originally Posted by Anemone

Four damsels and a clown in a 25 gallon tank may be pushing it. You don't say what type of clown, or what type of other damsels you have, but Dominos have a maximum size of 5", and can easily grow to 3+ inches. Depending upon the type of clown, it could also grow to 4+ inches.

Beyond the size issues, you could also have significant aggression. The bigger most damsels get, the nastier they get, and many damsels don't like other damsels. Clowns also get more aggressive as the age/grow too (they're damselfish as well!).

Good luck!

Kevin

Thanks for the information. I consider this to be the max I would ever have in this tank. I did notice some agression from one of the yellow tail damsels when I first added the Dominos, but it all seems to have calmed down now.

But I didn't really consider how big they might get. If I can get them to start smoking ciggarettes will that keep the size down? (-;

Sk8r · 06/18/2019, 03:34 PM

If you possibly can, return the dominos. Give them away. They'll do in the others. I've had a 'balanced' aggression damsel tank at 100 gallons, but a smaller one, no.

06/10/2019, 04:46 PM	#1
TwoShoesOrOne Registered Member Join Date: Jun 2019 Posts: 37	Calculation for # Fish I've seen a few rules of thumb about bio load (such as 1" of fish per gallon), etc. I was wondering if you should use the total volume of the system (display and sump) or just display? Thank you.

06/10/2019, 04:52 PM	#2
lpsouth1978 Registered Member Join Date: Jan 2007 Location: Arizona Posts: 915	This is a VERY general rule and will vary by fish. But to answer your question, I would use total system volume. Also it is 1" of fish (full grown) per gallon. Make sure you calculate based on the max size of each fish. __________________ Current tank: 40B work in progress w/20L sump

06/10/2019, 05:52 PM	#3
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	And I'll answer its only display gallons and not total system gallons.. __________________ Who me?

06/10/2019, 06:07 PM	#4
lpsouth1978 Registered Member Join Date: Jan 2007 Location: Arizona Posts: 915	And this is why it is a general rule. There is no single correct answer. Some tanks can handle more fish than others, a lot of things will influence how many fish your system can hold before becoming a problem. __________________ Current tank: 40B work in progress w/20L sump

06/10/2019, 06:42 PM	#5
Anemone Cloning Around Join Date: Jun 2000 Location: Valencia, California Posts: 25,267	Quite frankly, it's a ridiculous rule, that fails to take into account inter- and intra-genus aggression, tank dimensions (a long tank isn't the same as a tall one) and type of fish (tell me an inch of dartfish equals an inch of tang)... Kevin __________________ Back in the pool, swimming with the sharks... Current Tank Info: Red Sea 425XL w/Kessil AP700, Vertex 180i Skimmer, 2 x Vortech MP40s

06/10/2019, 07:59 PM	#7
Sk8r RC Mod Join Date: Feb 2006 Location: Spokane WA Posts: 34,628 Blog Entries: 55	The most common mistake people make in stocking (outside of not knowing aggression level, which is often a function of overcrowding and panic) ---is not realizing these fish are shipped at a 'shippable' size, ie, tiny. Our store has an ever-so-cute 1.5" rabbitfish. The kicker is, it gets 10" long real fast and is venomous to boot. It gets more and more freaky as it grows and lacks room. This fish attacks when spooked. So ---look at the adult size, and plan for that. Don't think you can trade a 10" rabbitfish back to the lfs. They can't accommodate him, and finding a fellow hobbyist that wants him is real hard. __________________ Sk8r Salinity 1.024-6; alkalinity 8.3-9.3 on KH scale; calcium 420; magnesium 1300, temp 78-80, nitrate .2. Ammonia 0. No filters: lps tank. Alk and cal won't rise if mg is low. Current Tank Info: 105g AquaVim wedge, yellow tang, sailfin blenny,royal gramma, ocellaris clown pair, yellow watchman, 100 microceriths, 25 tiny hermits, a 4" conch, 1" nassarius, recovering from 2 year hiatus with daily water change of 10%.

06/10/2019, 08:15 PM	#8
j.falk Registered Member Join Date: May 2017 Posts: 632	And with that being said rabbitfish sales plummeted to an all time record low.

06/10/2019, 09:08 PM	#9
TwoShoesOrOne Registered Member Join Date: Jun 2019 Posts: 37	More confused Okay, very simple rule of thumb is silly I agree. But if we are talking about bio load on the system I guess a good medium would be to consider a number based on being between the display and total display sump. So it might be between 4 and 8. I have a 25 gal displapy and 25 gal sump (filled to 15 gal) and 6 small fish which shouldn't grow too big I think 1-clown 2 damsels 2 spotted dominos 1 fire goby. Thank you.

06/10/2019, 09:17 PM	#10
bshow24 Registered Member Join Date: May 2012 Location: Thousand Oaks, CA Posts: 584	Bio load isn't necessarily based on the sump. It's based on how much area there is for beneficial bacteria to grow, which typically is live rock and sand in the display. Of course if the sump has a decent sized refugium or some filtration process to help the bacteria (siphorax comes to mind) then of course that can help with bio load. I personally take this process as a 2-step thought. 1) How many fish can fit in my DT? Once I get this answer then 2) Can my bacteria handle that? __________________ Tank: Reefer XL 525 Reef Tank Equipment: 2x Radion XR15 Pro, Radion XR30 Pro, Vectra M1 Return, 2x MP40 Powerhead

06/11/2019, 03:55 AM	#12
j.falk Registered Member Join Date: May 2017 Posts: 632	Dominos can get very aggressive as they get bigger. I know that from personal experience.

06/18/2019, 03:34 PM	#14
Sk8r RC Mod Join Date: Feb 2006 Location: Spokane WA Posts: 34,628 Blog Entries: 55	If you possibly can, return the dominos. Give them away. They'll do in the others. I've had a 'balanced' aggression damsel tank at 100 gallons, but a smaller one, no. __________________ Sk8r Salinity 1.024-6; alkalinity 8.3-9.3 on KH scale; calcium 420; magnesium 1300, temp 78-80, nitrate .2. Ammonia 0. No filters: lps tank. Alk and cal won't rise if mg is low. Current Tank Info: 105g AquaVim wedge, yellow tang, sailfin blenny,royal gramma, ocellaris clown pair, yellow watchman, 100 microceriths, 25 tiny hermits, a 4" conch, 1" nassarius, recovering from 2 year hiatus with daily water change of 10%.