This makes me take the whole "a fish needs so many gallons" with a few grains of salt

[reefgeek84]

Ok, so everyone talks about this fish needs so many gallons to in a tank...but I have always taken that with a grain of salt. Now do not get me wrong I would not put a nurse shark in a 75 gallon tank or a gray angle in a 50 gal tank, but I do not listen to this whole debate to much...My examples...

 

www.liveaquria.com states a potter's angle needs min 30 gals and marinedepotlive.com claims it needs min 100gal.

 

-Marine Depot

"Maximum Size: the Centropyge potteri grows up to 5 inches.

General Size Specifications: The dwarf angels will come to you generally 2 to 4 inches

Minimum Tank Size: The Potter's Angel prefers a tank of at least 100 gallons with plenty of places to hide & swim.

Diet: The Centropyge potteri is a omnivore and likes to eat marine algae, mysid shrimp, Spirulina, and other meaty treats.

Level of Care: The Potter's Angel is a medium maintenance fish.

Behavior: The Potter's Angel may act semi-aggressively toward other fish.

Water Conditions: Keep water quality high (SG 1.020 - 1.025, pH 8.1 - 8.4, Temp. 72 - 78° F).

Range: Hawaii, Hawaiian Islands.

General Notes: Centropyge potteri, Jordan & Metz 1912, Potter's Dwarf Angel, is another fish found only in Hawaii. Able to get along with other Pygmy Angels in a tank of at least 75 Gallons or more, due to territoriality. Very shy, and secretive as well, the Potters Angel does not readily adapt to captivity, and is not a fish recommended to be kept in an aquarium. If one chooses to try this fish, it should only be tried in a Reef tank of 100 gallons or more. "

 

Liveaquaira-

"The Potter's Angelfish requires at least a 30 gallon, well-established tank with multiple hiding places and live rock for grazing on microalgae. It may attack soft corals and other sessile invertebrates in the reef aquarium. "

 

Even the pros can not come to a general consenses...

[rude944]

Diving in Kauai recently,I saw many potters angels in every nook and cranny I approached. It was so abundant, I was shocked over the relative prices in our LFS. I feel, after seeing them in the wild, that the higher gallon requirement is the correct way to go. These are grazing fish, and the rock work required to support their feeding should be immense. It is unlikely that they will have their needs met simply by food added to the tank, and this is my reasoning for the higher gallon threshold.

 

I think every experienced individual should research and understand the fish they put in their tanks, as these SW fish are expensive investments. We are in a specialized hobby, which requires a lot of knowledge and intelligent application.

 

Use your educated judgement before you add anything is the bottom line, right?

[reefgeek84]

Diving in Kauai recently,I saw many potters angels in every nook and cranny I approached. It was so abundant, I was shocked over the relative prices in our LFS. I feel, after seeing them in the wild, that the higher gallon requirement is the correct way to go. These are grazing fish, and the rock work required to support their feeding should be immense. It is unlikely that they will have their needs met simply by food added to the tank, and this is my reasoning for the higher gallon threshold.

 

I think every experienced individual should research and understand the fish they put in their tanks, as these SW fish are expensive investments. We are in a specialized hobby, which requires a lot of knowledge and intelligent application.

 

Use your educated judgement before you add anything is the bottom line, right?

No I totaly completely agree with you. But the internet is out main way of learning and researching what we want to get...but then you come across that and see a 70gal difference, that makes it tough for someone to decide if they can have that fish or not. All the books I have claim any where from 20-40gals for that fish.

[andy]

As a relative newcomer to the hobby (returning after a 20 year absence), I've really noticed wide discrepancies between various sources of information. I think we're at a transition point in the hobby; in the past couple of years, we've made some amazing advances and are coming to understand the marine systems we're trying to mimic much more fully. It is only natural that the 'old' information takes a while to decay -- in some cases, it'll live on as 'old wives tales' that we'd love to get rid of but never will be able to

 

One of the biggest places I've noticed this old vs. new is with system requirements for many of the challenging (formerly impossible) species. Maybe the different information listed at Marine Depot and Live Aquaria are another example of this?

[H20cooled]

One other factor is how effected is your waste processing system on your tank. Is your skimmer big enough to handle the waste, is it plumbed so that it is effectivly pulling out the waste (i.e. surface scum removed and going into skimmer), is your flow strong and setup correctly to keep the waste suspended? These are all factors that will effect your tank and really how many fish you have in there. I've seen system with very good designs and skimming that can be stuffed with a LOT of fish, and the tank thrives like that.

 

Rich

[Twitterbait]

I totally ignore their specifications. I simply take into account the following things and judge for myself.

 

1.max/average size the fish will get in captivity

2.waste production

3.how much the fish actually like to swim around

4.how fast the fish will swim

5.special feeding requirements that may need a bigger tank to support the fauna

 

so far i have done pretty good.

[JManrow]

According to the seminar I took a few years ago, one should not place more than one pound of living organisms (the emphasis was mainly on fish... also use of denitrification filtration, such as using liverock, was not included in this calculation.) per 100 gallons... or 1.6 ounces per 10 gallons. That's why you must figure tank loading capacity by weight to system volume. This calculation applies to the ability of a system's biological filtration to process waste. Other factors that affect what can be in the tank include water volume turnover rate, the amount of surface area of biological filtration media, compatibility of tank occupants, and territorial requirements for a particular animal.

The old rule of thumb about about so many inches of fish per so many gallons of water can only be applied to very small adult fish. A 2 inch damsel, for example, may weigh 6 to 8 times as much as a one inch damsel. That means that 2 inch fish is 6 to 8 times the bioload than the 1 inch fish.

[andy]

Interesting. Any mention of how much fish weigh? I have no idea...

[Guest Ahbrit]

time to get the scales out

[JManrow]

Fish Weight Calculator

 

I have a worksheet with diagrams to calculate the weight of a fish, but do not have a working scanner. Instead, I will give descriptions.

 

Laterally-compressed Fish: Butterfly; Trigger

 

Torpedo-shaped Fish: Fire Goby; Eel

 

---------------------------------------------------------------------------------------------

TO CALCULATE FISH BODY WEIGHT, follow these steps.

 

For laterally-compressed fishes;

 

1. Draw a circle that fits roughly within the side body dimensions of the fish.

2. Measure the diameter of the fish in centimeters.

3. Divide the result by 2 to get the radius.4. Multiply the radius by itself to get the radius squared.

5. Multiply the radius squared by 3.14

6. Multiply the result by the thickness of the fish.

 

The result of your calculations is the weight of the fish in grams.

 

For torpedo (cylindrically) shaped fishes;

 

1. Draw a circle that fits the widest part of the fish's body.

2. Do the calculations outlined in steps 2 through 5 for the laterally-compressed fish.

3. Measure the fish's length and multiply it by 0.75

4. Multiply the results of steps two and three.

 

The result is the fish's weight in grams.

To convert to ounces, divide the weight in grams by 28.35

 

Copyright© 1988 by Richard M. Segedi

[oldbrownies]

thats alot of fish, but I would say its about what I would consider a "heavily stocked" tank

[fly guy]

I think the whole "pounds per gallon" needed for fish is just as silly a notion as the "lbs of rock" needed per gallon in our reef tanks.

 

I always get a kick out of it when you hear people say they have 200 lbs of rock in their 80 gallon tank in order to get maximum biological filtration. First of all if you can even fit 200 lbs of rock in your 80 gallon tank......your rock is dense worthless crap and or stacked WAY too tightly together so there is now way you are even getting flow through it making it essentially worthless. Good light porous rock and flow through it.........I think you can do a much better job with less than more.

 

As far as the fish thing.......its all equipment, husbandry practices, and set up. If you can feed them and get the nutrients out, you can keep as many fish in there as you like. There is no magic number based on gallons to tank size. A guy with a well planned, high flow BB tank with a huge skimmer will be able to keep a lot more fish than a guy whos tank ha low and or poorly planned flow and mediocre skimming and husbandry pratices.

 

There are obviously some fish that simply need tanks of a certain size to be happy and healthy. But we arent talking about that here i dont think.

[tidalsculpin]

I agree with fly guy about maintenance and design. I don't know a lot about potter's angle fish.

 

I do know that as I have learned more about maintaining water quality in my tank it handles a few more fish than I thought it would.

 

One question to Jmanrow-- the calculation on fish weight assumes fish have a density of 1.0 gm/L. Is this always true?

[JManrow]

I agree with fly guy about maintenance and design. I don't know a lot about potter's angle fish.

 

I do know that as I have learned more about maintaining water quality in my tank it handles a few more fish than I thought it would.

 

One question to Jmanrow-- the calculation on fish weight assumes fish have a density of 1.0 gm/L. Is this always true?

 

The information and calculations that I posted were from a course I took offered a few years ago by Richard M. Segedi, a biologist then with Cleveland Aquarium. He states that using that chart, the results are usually within 10 percent of actual weights, which should be accurate enough for general use. (I always try to be able to back up what I post with some kind of fairly credible documentation. I had no intention of my former post to be in any way "silly", but to each his own opinion. In my opinion, R. M. Segedi is a reputable source of information.)

 

Segedi, along with W.E. Kelley, modified the Frankfurt Aquarium formula for artificial seawater mix. (Segedi, R. and Kelley, W.E. (1964) A new formula for artificial seawater.)Their formula is the basis of all saltwater mixes used today. Listed here under ANNEX 5 - Artificial seawater formula) http://www.fao.org/docrep/008/y6018e/y6018e06.htm

 

The other reference was to a general guideline about the ratio of fish weight to aquarium system volume. It was simply stating that the waste produced by fish of a given weight, could be assimilated most efficiently by nitrogenous bacteria on a given minimum amount of surface area of filter media, with a minimum turnover rate for nitrification. The 16 ounces per 100 gallons was a maximum bioload per a minimum filter surface area and complete system volume turnover rate(1 sq. ft. of surface area, per gallon, per minute with water turnover through the system and attached filters at least once per hour. Again, these are minimum requirements for a maximum bioload.

[fly guy]

I had no intention of my former post to be in any way "silly", but to each his own opinion. In my opinion, R. M. Segedi is a reputable source of information.)

 

.

 

 

Just to be sure jmanrow......i would like to clarify that my post (and use of the word "silly")was not at all aimed directly at you or your post. I apologize for writing it in such a way that could be interpreted as such. Was not my intention. : )

 

I was just stating my opinion in reference to some of the many "rules" to this hobby that have far

too many variables to simply attach a number to.