Fish Size!

[LittleParr]

When purchasing fish for a saltwater tank, how do you know how big the fish will grow? What if they outgrow the tank?

 

[TCTFish]

Whenever you are interested in a particular fish, always read up on that fish. Books will tell you their adult size and if that adult size is too big for the tank you have...do not buy the animal.

 

[tecwzrd]

www.liveaquaria.com is a pretty good reference site for determining fish requirements and total adult size. They are not always accurate on the needed tank size though. I’d recommend using the fish calculator on this site to figure out how many inches of fish your tank can handle. Of course that doesn’t mean you can keep something like a blue tang in a 55 gal just because you are allowed 11”

 

[LittleParr]

Where's a good spot to find info on the max size each fish will grow?

 

[tecwzrd]

On liveaquaria look for “Max size in Aquarium”

 

[LittleParr]

Sorry...I clicked on report by accident when using the side bar.

 

[Jchillin]

No problem...thanks for letting us know.

 

[Hara]

It just so happens that this afternoon, we opened the doors to the database on
www.fantasyreef.com (click the link for database at the top of the page). It will be a continuous ongoing project but the search features are working. Pick which database you want, in this case fish, and choose the search you need.

Please report any malfunctions you may encounter, but have fun with it! There is a search on tank size that should tell you what you want to know.

 

[melosu58]

Also most fish will not grow to max size in a tank anyway. Unless it`s a super sized tank.

 

[Macrosill]

When determining the amount of fish you can put in a tank does it go by tank volume or total water volume including the sump? I have a 55 with a 55 sump. Do I calculate it to 11" or 22"? Well actually shy of 22 because the sump will not hold 55 gal, need room for sand and lr in the refugium and room incase power goes out.

 

[tecwzrd]

I’d go by tank volume unless you plan on having your fish swim in your sump

 

[Macrosill]

So amount of fish has to do with the physicxal size of the tank and not the bioload on the system?

 

[tecwzrd]

Yes and no. The “calculator” is more of a guideline. Just because you have 11” (minus tail) to play with in a 55 gal doesn’t mean you should keep a 11” fish obviously so it’s confusing to a lot people on just how many fish you can/should keep.

Say you have 90 gal to play with which does help in keeping your nh3, no2, and no3 levels down ie: “the solution to pollution is dilution” you hear so much. With such a large sump your levels may be perfect even with a lot of fish but it of course doesn’t increase the area they can swim in. Main reasons you want to avoid overstocking is two fold in that it can increase your nh3, no2, & no3 levels significantly (which you wouldn’t have to worry about as much) but also to help alleviate territorial issues.

Fish selection will play a much more important roll than quantity in your case and IMO you could get away with a few more fish than the norm assuming you choose fish that are highly compatible.

 

[tecwzrd]

In case you don't see it fishfreek said it better than I just did.

My definition of overstocked is very simple.

If all your pumps fail for a period of 12 or more hours will your fish sufficate due to lack of oxygen? If so your overstocked no mater how well your water conditions are when all your equipment is running.

With that said I also feel that 2-3 fish would be the max for a 20 gal tank. Given its a 20 long you can technicly get by with more fish than a 20 H because there is more surface area for gas exchange but you also must take into account the fish's agressivness as a factor when it comes to overcrowding.

I hold to the school of understocking. As an example I have a single yellow tail damsel in my 20H, a flame angel, bicolor damsel, yellow tang in my 75 and in my 80 a powder blue tang, coral beauty, hawk eye goby, and two yellow gobies. I have seen people have all those fish in a single 75 before. If your pumps work than they can live with out issues but if your pumps fail for a period of a few hours you will have deaths.

 

[melosu58]

Sometimes you cant go by gallons and have to go by length or depth. Tangs need plentyof swim space and length is important. A 125 is a good size for them because they are 6 ft long and have more length for swimming than a 55.. So sometimes there is more to consider than gallons only.

 

[Macrosill]

okay, now the fish selection process is getting complicated. The quote "nothing good in this hobby happens quickly" rings true here. Alot of research take a long time.