How To Pick Out a "good fish"

Discussion in 'Saltwater Fish' started by Humblefish, Sep 3, 2020.

  1. Humblefish

    Humblefish Active Member

    Nov 9, 2018
    Likes Received:
    Once upon a time, most of us actually went into a Local Fish Shop (LFS) to pick out our fish in person. So, this write-up is geared more towards those who still pick out their fish as opposed to just ordering online. Sometimes ordering livestock online is like getting a box of chocolates... UNLESS you are buying (shameless plug coming) from a HF approved vendor that only sells WYSIWYG quarantined, conditioned fish:

    So, you walk into your favorite LFS and see all these amazing fish. What should you be looking for?
    1. Bright colors - A pale fish could just be an indication of stress, but it can also be a sign of disease. Not worth the risk.
    2. Fins & spines are on FULL DISPLAY - Clamped fins are sometimes also just a stress indicator... but can also be a symptom of disease. Again, not worth the risk finding out which it actually is.
    3. BIG PLUS if the fish is out swimming or is actually being sociable with you - This is sometimes an unrealistic expectation, as most fish at a LFS tend to hide. That behavior is pretty normal because the fish is still trying to figure out its territory and has not yet adjusted to aquarium life. But if you do see a fish you like swimming out in the open or even interacting with you through the glass, that is a very good sign!
    4. Avoid fish with visible physical symptoms of disease or injury - White dots or splotches, stringy mucous coming off the fish, red sores or streaks, fin erosion or body damage are all bad signs. The fish should look flawless! Discoloration sometimes is just due to a fish's stress pattern, but you should observe the fish for a while to see if coloration returns to normal.
    5. Avoid fish with behavioral signs of disease - Heavy breathing, scratching/flashing, head twitching, yawning, erratic swimming behavior. These last two are somewhat unique to Marine Velvet Disease and fish with these symptoms should be especially avoided: Swimming into the flow of a wavemaker or powerhead, and fish which seem to be purposely staying out of the light (Velvet causes fish to be sensitive to light).
    6. DO NOT buy any fish which shares water with a diseased fish - Keep in mind that many Local Fish Shops have some or all of their tanks plumbed together with a common sump. Sometimes there is a UV sterilizer plumbed into the common return line, but you still have to consider three things: a) Is the flow rate slow enough to eliminate pathogens? b) Cross contamination via nets and wet hands c) Aerosol transmission.
    7. Ask the LFS if their fish are being kept in copper or some other medication(s) - This is not necessarily a dealbreaker, but just know that fish kept in subtherapeutic copper will oftentimes look/act better than they actually are. The low copper is just keeping the parasites at a sublethal concentration. Once the fish is removed from this environment and placed in non-medicated water, many times the parasites are able to then multiple and overwhelm a fish's natural immune system. And spread disease throughout the entire tank. One thing you can do is find out (and double-check yourself) what copper level the fish are being kept in and then set your Quarantine Tank (QT) to match. You can then raise the copper up to full therapeutic, and finish the job that the LFS began for you.
    8. Ask to see the fish eat - I cannot stress the importance of this enough! DO NOT buy a fish unless you see that it is eating. If a LFS refuses to feed the fish for you, either walk out or ask when is feeding time so you can return later. Do not leave that shop without whatever food you saw the fish eat! An eating fish gives you at least a fighting chance with it.
    9. It's never a bad idea to study the fish you want to buy - Make daily visits to the LFS (if possible) to see how your potential fish purchase is doing. Of course, you risk that the fish might be purchased by someone else but another fish you like even better may come along instead. Be patient.
    10. Use a magnifying glass - IF you can get close enough to a fish for this, use a magnifying glass (many smart phones have this feature built-in) to more closely examine your potential fish purchase. You'll be amazed what you can sometimes see under a magnifying glass that your eyes completely missed!
    Assuming you have a short journey home, you can acclimate using one of the methods outlined here:

    Ask what salinity the fish is being kept in at the LFS, but verify this yourself by sticking a small needle through the bag (just above the water line), take a water sample using a pipette and then quickly close the tiny hole using a piece of scotch tape. If SG of the bag water is within 0.001 (+/-) of the receiving tank, you can just float & release after 30-45 minutes (to temperature acclimate). Any salinity outside of that range will require a drip acclimation as outlined in the article above.

    Using a quarantine tank for your new fish purchase(s) is HIGHLY RECOMMENDED:

    One of the nice things about using a Quarantine Tank, in conjunction with buying from a LFS, is you can set water temp & salinity to match whatever the store normally keeps their fish in. By constantly maintaining these parameters in your QT, you are always ready to buy a new fish! You can then raise salinity (if needed) to match your display tank for when the fish is out of quarantine. I typically accomplish this by topping off with saltwater instead of RODI.

    Whether to prophylactically treat or just passively observe in QT is a personal choice, and is discussed further in this article:
    StirCrayzy and DaveK like this.
  2. DaveK

    DaveK Well-Known Member

    Nov 21, 2003
    Likes Received:
    Philadelpahia, PA
    This is a good post. I'd like to add a few finer points.

    Above all, does the fish look and act like it is supposed to for the species. SW fish have a lot of variation and what would typically be normal may not be normal for the species being considered.

    On bright colors, yes pale colors can be a sign that something is not right. So can colors that look too bright or intense. This can often indicate stress.

    On fins and spines, yes clamped fins can mean a problem, but there are also some species where the fins looked clamped, but that's normal for the species. Fins and spines in a fully extended position can also be an issue, again usually an indication of stress. On tangs, make sure the tail spines are intact. It sometimes happens that the spines were clipped by the collector. Such a fish is damaged and you don't want it.

    On avoiding fish from which shares water with a diseased fish, this is very difficult today, since many stores use a common system for all tanks. Best thing to do here is to consider the overall health of all the fish in the system. If you see a lot of problems, walk out.

    On asking if the LFS is using copper or other medication. A lot of LFS people will not know or just say no because it's easier. Consider any water you get from the LFS tanks to be contaminated in some form, and never ever add any of it to your system. If a LFS is running copper, it only takes a little water from that system to wipe out your corals.

    On seeing a fish eat. Generally this is an excellent idea, but sometimes it's really hard to see if the fish is actually eating or it's just chomping at the food and spitting it out. Also because so many other people might have been asking to see the fish eat, the fish just might not be hungry. Because of this I now use the following rules. If the fish is know to be a fussy eater, then yes, it's got to eat. An example would be a copperband butterfly. If it will not eat reject the fish. If it's a fish that normally doesn't have feeding issues, and it looks healthy then seeing is feed is not so critical.

    When looking over a fish, also make sure it's not thin for the species. This not only applies to the belly, but also the area above the lateral line. If that area looks thin, it usually means the fish isn't doing well. This is often seen on tangs and related species.

    Lastly, don't buy a fish that you don't know anything about. You don't want to get something that will eat everything in your tank, or be impossible to feed. Don't depend upon the LFS to know either, especially if it's an unusual species.
    StirCrayzy and Humblefish like this.
Similar Threads Forum Date
least pickiest clownfish species to host Saltwater Fish Jul 14, 2014
How to pick up women at the fish store FaceBook Plugs Aug 8, 2013
Clownfish picking at rocks Saltwater Fish Feb 25, 2013
help picking out a few more fish for my tank ? Meet & Greet Forum Feb 21, 2013
If you could do it again: What reef frendly fish would you pick for a 150 tank? Saltwater Fish Nov 20, 2011

Share This Page