Buoyancy Issues in Aquarium Fish – Common Aquarium Questions

As you may know, our Marine Bio Staff here at That Fish Place works tirelessly answering fish and aquarium questions by phone, email, in person, and of course, on That Fish Blog.  We thought it might be helpful to periodically post some of the answers to FAQs here in the blog as an added resource to common issues and inquiries.  Please don’t hesitate to contact us for info, we’re here to help!  And keep an eye on That Fish Blog for more FAQs and answers, info and advice!

Dale in Pittsburgh wrote:

I have a 30 gal freshwater tank, with 17 tetra-type fish (Bloodfins, Glow-Tetras, Neon-Tetras, Black Tetras, etc) and I have noticed that there are some buoyancy issues, particularly with the neon tetras (3 out of 5 fish). They are not new, they have been around for quite some time, and I cannot recall any changes that have taken place in the last few months. They have an issue with nose down, tail up syndrome, constantly trying to swim down to keep neutrally buoyant in the water. Any ideas why this would occur?

Tank equipment:

Under-gravel filter with a Marineland 660 Powerhead

Emperor 280 filter (diamond blend carbon / ammonia) with a standard gauze filter in-front for fine particulates

Marineland 200 stealth heater (set to 78 deg, room temp 75 deg)

2″ mixed gravel

Artificial Plants

Artificial driftwood

1 piece of gray slate (I think)

I feed Tetramin flake food once daily Mon-Friday (9am), the tank location is in my office.  I do 10 gallon water changes every 2 weeks, and water tests with master test kit results are as follows: slightly high PH (7.2-7.5 avg), ammonia and nitrite 0 ppm at every test, nitrate is around 10-40ppm average.

Answer from MarineBio@thatpetplace.com:

From what you have described, they could have infections in their swim bladders. Typically when you see fish having that problem, the culprit is a bacterial infection in the swim bladder. This can be difficult to treat, but there is one medication that we have had good luck with. Seachem makes a product called Kanaplex (kanamycin sulfate), that has proven effective against internal infections. You can dose your entire tank with the medication, just make sure that you remove the carbon from your filters first, as it will absorb medications from the water. The directed treatment is dosage every other day…. but to be honest, you can dose daily for 7 days and see if you get better results. It should not affect your fish if you increase the dosing frequency to once daily. Just perform a water change on day 3 and you should be just fine. Good luck!

Please write in here if you have any questions or further advice on this question.

Happy Holidays from That Fish Place

Thanks for being a loyal That Fish Blog reader in 2008! Have an excellent holiday and please accept this exclusive gift from ThatPetPlace.com 10% off your order over $80. Use promo code “HOLIBLOG” at checkout. Offer valid until January 2nd, 2009. 

Red Sea Star

Enjoy the holidays. New articles will be back December 26th.

Until than,

Happy Holidays from Dave, Frank and the rest of the ThatPetPlace.com Marine Biologists and Staff

The Ocean Sunfish or Mola Mola

Melissa here. When you think of fish that are swimming around in the ocean, most people think of clownfish and damsels swimming around through the tentacles of anemones with corals and live-rock creating the backdrop of that picture perfect image. Ever wonder what is out beyond the reef? There are many awesome creatures that lurk around in the middle of nowhere, far away from the beautiful reef. One of these awesome fish is the Ocean Sunfish, or Mola Mola. Ocean sunfish are the largest known bony fish, weighing in on average 2,000 lbs for an adult. One of the largest Ocean sunfish ever recorded weighed nearly 5,000 lbs!

Ocean sunfish are usually seen near the surface in open water, swimming upright or on their side soaking up the rays or the sun like a large solar panel. Don’t let their position side fool you into thinking they are sick. It is theorized that they “sun” themselves to warm up from a deep dive. It is known that they also spend a great deal of time below 200 meters. That is quite a ways down.

Ocean sunfish are among the strangest looking fish. The posterior half of their body appears to be cut short. They do not have a caudal fin, instead they have clavus which is an extension of their dorsal and anal fin rays. The fish is laterally compressed, looking like a large oval with a paddle shaped fin on the top and bottom. Their skin is like gritty sandpaper covered in a mucus layer that can be as thick as 5 cm. They are also loaded with internal and external parasites (there is a link at the end if you would like to see the list of parasites that cover the ocean sunfish). Juveniles resemble puffers with their large pectoral fins, a tail fin and body spines that are uncharacteristic of adult sunfish.
Their diet consists mainly of jellyfish, squid, crustaceans, small fish, and lots of zooplankton. As its diet suggests, the Ocean sunfish feed across the ocean depths, from the surface to deeper waters, and in some areas, even the ocean floor. You can only imagine how much food these fish must eat on a daily basis to sustain themselves! They are very difficult to keep for long periods of time in captivity, even in the largest system, so Ocean sunfish are not seen in many public aquariums, but there are a few that have taken on the challenge of keeping them on display. The Kaiyukan Aquarium in Osaka, Japan and The Oceanario in Lisbon, Portugal both have Ocean sunfish on display. In the United States, The Monterey Bay Aquarium is the only one to house a mola mola. The longest known ocean sunfish in captivity made it 10 years. In the wild, they can live 100 years or so. Their growth rate is still undetermined, but a young Mola Mola at the Monteray Bay Aquarium went from a slim 57 lbs to 879 lbs in a mere 15 months. It also sprouted to a height of nearly 1.8m. Fattened up on a diet of squid, fish and prawns, this fish had to be airlifted out by helicopter and released into the bay after outgrowing its tank.
It is generally accepted that ocean sunfish larvae will become millions of times bigger during their life cycle. As you can see, this is definitely not a fish you would find at That Fish Place, but you might come across it while scuba diving, so keep your eye out. Ocean Sunfish are found in both temperate and tropical waters. A lot that remains unknown about the secret lives of ocean sunfish!
Here are some great websites about ocean sunfish: http://oceansunfish.org/ has a fun map showing sightings of ocean sunfish
http://www.earthwindow.com/mola.html has awesome pictures of ocean sunfish.
http://www.oceansunfish.org/lifehistory.html this site has a list of parasites that have been found on ocean sunfish.

Image referenced from Wikipedia.

Our Favorite Aquarium Books

Desiree and I have both shared some of our favorite aquarium websites and virtual reference, but what about those times when you want a real, live, glossy-paged, paper-cut-compatible BOOK? Well, just in time for the holiday shopping and wish list season, here are a few of our favorites of those, too.


  • Dr. Axelrod’s Atlas of Freshwater Aquarium Fishes and Dr. Burgess’s Atlas of Marine Aquarium Fishes
  • These two books are some of the classic tomes of aquarium fishes. Both contain literally thousands of species of fish as well as some basic information about each one. These books won’t help with aquarium-related details, but they are must-haves for identification and sheer volume of the animals covered.
  • Pocket Expert Guides (Reef Aquarium Fishes and Marine Fishes, both by Scott W. Michael, and Marine Invertebrates by Dr. Ronald L. Shimek)
  • This series is one of my personal favorites. Compact in size, but certainly not in information, these books are written with the aquarist in mind. They each contain well over 400 species of animals with detail on care, compatibility, aquarium suitability, maximum size, minimum tank size and other pertinent information. It’s a great series to take to the fish store with you for a quick reference on your new purchases.
  • “The Simple Guide” and “Super Simple Guide”series
  • This is the perfect series for new aquarists and is one of the first we tend to recommend when someone mentions “I’m thinking about starting a _______ aquarium”. The information is presented in a way that isn’t overwhelming to new aquarists and provides a complete view without getting too bogged down in scientific equations and technical terms. No matter what type of aquarium you have or are thinking about getting, there is probably a Simple Guide for it.
  • Reef Invertebrates: An Essential Guide to Selection, Care and Compatibility, by Anthony Calfo and Robert Fenner
  • I think we are currently on our…fourth?…copy of this book in our Fish Room because our employees wear it out reading and re-reading it during their lunches and free time. Lots of information about a wide range of invertebrates. A good read for “Reef” and “Fish-only” aquarists alike.
  • Corals: A Quick Reference Guide, by Julian Sprung
  • Ever see a new coral that you absolutely must have, but you know nothing about it? Look it up in here. Ever see a coral but can’t figure out what it could possibly be? Look through here. Need ideas about what new corals you could add to your existing reef tank? Browse this book. Lots of common aquarium corals with compatibility, identification and propogation basics.
  • Aquarium Fish magazine
  • Ok, so its not technically a “book”, but it still counts. This monthly magazine is by aquarists and for aquarists. It includes information on both freshwater and marine aquariums and is geared towards new and experienced hobbyists alike. I have a binder filled with past articles that I just HAD to save from this magazine. The new species profiles alone will never let us run out of new animals and aquariums to try at home.

Have any favorites I didn’t mention? Looking for a good book on a particular subject? Let us know!



Feeding Egg Yolk to Fish Fry

Ever wake up one day, take a look in your tank and see a horde of tiny little baby fish that weren’t there the night before? Did you have to run out in search for something to feed the new little fish? Here’s a quick and nutritious solution that you probably already have on hand…egg yolk! Yep, normal old chicken eggs that are probably already in your refrigerator. Just hard-boil an egg and remove the yolk (you won’t need the white, feel free to munch on that while you prepare the fishes’ portion). Put a small piece of the yolk in a small container of water and shake it up until the yolk is completely suspended in the water. You may want to break it up a little before you start to get a headstart but if you still notice larger chunks in the water that haven’t broken up enough, you can strain the mixture through cheesecloth or a coffee filter to get rid of the bigger pieces. Once the yolk is suspended in the water, just add a little to the tank with the fry. It’ll make the water a little cloudy so you don’t need to add much and you can save the mixture for a few days in the refrigerator.

Quick, easy, and healthy for just about any small fish fry!