Aquarium stocking tips – How do I choose my fish?

Eileen here. We’ve all heard some of the general “rules of thumb” for stocking an aquarium: an inch of fish per gallon, one fish per gallon, more fish = less aggression and countless others. So, what works best? There are several approaches that can help make stocking an aquarium easier.

Research, research, research!!

It’s no secret that I for one am a big fan of research. I’m not talking in depth taxonomic studies or long term observational studies, just a little planning and reading up on what you would like to keep. We get a lot of questions like “I set up a tank, now what can I put in it?” or “I bought this pretty yellow fish, what can go with it?”. You may be able to save yourself some time, frustration and possibly disappointment by planning out what you might like in your tank before setting it up or buying any fish for it. It also helps you decide what you would like to put in it down the road. That way, you will be able to decorate and filter your tank in the best way for what you’d like to keep and you’ll avoid getting those impulse-buy tankmates that eliminate any chance of having that special fish you’ve had your eye on for months.

Along these same lines, be sure you are aware of the behavior of each item you choose and its requirements. There is nothing worse than bringing a fish home, only to learn that you have to spend more time preparing its food than your own, or finding out that it is a known predator of that favorite fish you already had. A few basic aquarium fish books can help a lot with the basics and can even help you find fish you never even knew existed. You could try shooting us a blog question, email ( or giving the store a call at 717-299-5691 if you’re looking for help in this regard too.

An inch per gallon? Only sometimes

This is one of the most common stocking “rules” we hear but is often misunderstood and misused. Let’s compare a few common groups of freshwater fish: tetras, goldfish and cichlids. First, the “inch per gallon” or “fish per gallon” rules have to take the adult size of the fish into consideration. Sure a fish might be one inch when you buy it, but if that fish grows into a footlong adult? That changes things. Then, what about the body mass of the fish and the waste it produces? Six little one-inch-long tetras will certainly affect an aquarium different than a six-inch-long goldfish. Goldfish just produce a whole lot more waste, eat a lot more and have a lot more mass and size behind that six-inch-length than all of those little tetras put together. Next, what about the behavior? That same six-inch goldfish is going to have a far different temperament than, say, a six-inch Green Terror cichlid. Two six-inch goldfish could be perfectly happen in a well-filtered 45 gallon aquarium; the two Green Terrors may well try to kill each other. So do we throw out the “inch per gallon” rule altogether? Not necessarily. It is fine to use as a very general and basic guideline for small fish like tetras, danios or livebearers if you take their adult size into consideration, but don’t take it as gospel if you are keeping anything larger.

Zone Defense: It works in sports, it works in aquariums

When stocking your tank, keep in mind that all of the fish won’t be spending all of their time in the same area of the tank. Looking at your aquarium from the front, you can divide it horizontally into 4 zones. The middle two zones are where a lot of fish hang out. In freshwater, this is where you’d find tetras, angelfish, barbs, and some cichlids. In saltwater, this would be your tangs, damsels, clownfish, and some groups of wrasses. The top quarter section is more of the top dwelling fish. In freshwater, these are fish like hatchets, killifish, rasboras, and mollies and in saltwater, this would be some cardinals and dartfish gobies – fish whose mouths are more on the tops of their heads and point upward for those prey items on the surface. The last section, the one on the bottom of the tank, is home to the bottom feeders – catfish, blennies, loaches, and gobies. Some saltwater fish and freshwater cichlids that spend a great deal of their time in and around rockwork also would count towards this group.

Stocking an aquarium with all three sections – top, middle, and bottom – in mind will help you make the most of the space you have. Instead of having a lot of fish that hang out in one of these zones, choosing fish from all three can give you a more complete look to your tank and can help spread out the activity and aggression throughout the whole tank.

The more, the merrier? Or one big spotlight?

There are two big ways to plan an aquarium – having an active tank with lots of activity and schools of little fish, or have a showcase item like a big saltwater angelfish or showing cichlid and build the rest of the tank around it. Both can be stunning in their own way but take some planning. Having a tank full of different schools of little fish can be interesting and active. You can have a higher number of fish this way but there isn’t one big thing to focus on. Or, you can have one big fish like a Discus and complement it with just a few other little fish for some subtle activity and to help with clean-up. Some of the most interesting tanks can be species-only tanks. These tanks have just one kind of fish like an aggressive cichlid or a saltwater oddity like a frogfish, and nothing else. These are the true “pet fish”. They can be fascinating but aren’t as diverse as community aquariums.

Biotopes – a little piece of nature.

Some of my favorite aquarium have been biotopes. These are tiny pieces of a specific environment where everything in the aquarium is designed and chosen around that location or habitat. For examples, a Caribbean biotopes would have only fish and invertebrates chosen from the Caribbean, so a fish from the Indo-Pacific would not be chosen for this tank. This is how most public aquariums are designed and is one of the more collector’s approaches to aquariums. Instead of relying on the impulse buy, this method is all about planning and choosing the perfect addition for your little slice of nature. Much better than a postcard for remembering that trip to Hawaii!

These are just a few approaches to choosing the next addition to your favorite aquarium. Feel free to share your own and never be afraid to ask if you aren’t sure if what you want is right for you!

Feeding Canned and Live Insects to Marine and Freshwater Fishes – Part 2

Hello, Frank Indiviglio here.  I have always included insects in the diets of a great many fishes, including shallow-water marine species (in the accompanying photo, you can see a number of typical community aquarium species swarming around a cricket).  Please see Part I of this article for further information on the role of insects in marine and fresh water fish diets.

My Experience with Wild Fishes

Whenever I have the opportunity, I toss insects into natural water bodies.  Time after time, be I near a quiet pond in Ohio or a salt marsh on Long Island, the insects never last more than a few minutes before being consumed by resident fishes.  Eventually, I came to believe that terrestrial invertebrates play a great role in the diets of numerous freshwater, brackish and even marine fishes (many insects fly far out over the ocean, especially on migrations, or are carried there by the wind).

Current Research

Just this month (August, 2009), biologists at the National Oceanographic and Atmospheric Administration published the results of a research effort which addressed this very topic.  Surveys of fishes in lakes across North America have revealed that terrestrial insects comprise up to 100% of the diets of some fish species (my own casual observations are rarely validated in such a timely fashion!). 

However, in lakes where development has eliminated shoreline vegetation, insects typically make up only 2% of the diets of the same fish species.  The importance of insects is evidenced by the fact that fishes living in lakes with developed shorelines take in 50% less energy on a daily basis and grow slower than those in undeveloped lakes.  Fortunately, re-planting even a narrow fringe of bushes and grasses along a lake can dramatically increase terrestrial insect populations.

Canned Insects for Aquarium Fishes

Both live and canned insects are eagerly accepted by many typical (and untypical!) aquarium fishes. Canned invertebrates may be better suited for most aquarists, who, unlike their reptile-keeping colleagues, are not often in the habit of maintaining live insect colonies. What’s more, they retain all the nutrition of live insects but are far more convenient to store and use.

Canned grasshoppers and adult crickets are ideal for large carnivorous fishes such as Oscars and other Cichlids, arowanas and many catfishes, and can also be crushed or chopped for smaller species.  Other varieties of canned invertebrates include snails, mealworms, silkworms and young crickets . Freshwater shrimp , also available in cans, are eagerly taken by a wide array of fishes. 

Further Reading

In some habitats, the availability of “junk food” is reducing the role of insects in fish diets.  To learn more, please see

Please write in with your questions and comments.  Thanks, until next time, Frank Indiviglio.

That Fish Place Aquariums and Fish Recap – Week of 8/24

Ah, Friday. Best day of the week! Though there is never a lack of interesting fish/aquarium/ocean related news to reinvigorate us and carry us through. Let’s take a look at the news and newbies!

  • Blue TunicateThe Grunion are running! AHHHHH! Actually, if you don’t know what grunion are and you’re concerned about why they are running, don’t worry, it’s actually a good thing. This might be something I would put on my bucket list of things to experience before I die. (I’m easily amused.)
  • Of course I’d much rather be faced by thousands of little fish than have “Died of Toxic Algae Gases” imprinted on my death certificate. Visiting the French Coast is off my bucket list. Of course it will be something to reconsider if they get the situation under control in the next (hopefully) 50 years or so.
  • Snooty WrasseIf anything could be more exciting than the running of the grunion, check out the image captured by Google earth!!! I always knew she was there somewhere, not even Nessie can escape the spying eyes in the sky!
  • I can’t imagine that the guy in this article has much left on his list if he has one. Seems to me if he wants to do something he has little trouble accomplishing his goals. This guy is pretty amazing IMHO, but not just for his endurance, but for his guts at swimming in some of the rivers and conditions he has. We aquarists all know what lurks in the muddy depths, so this guy gets a big WOW “what a crazy-cool thing you did!” from me!
  • Spotted Pike Characin Everybody has an opinion on goldfish in the aquarium world, and sadly, the opinions are not always good. But when you see those bulging eyes and that bobbing, bulbous body, its hard not to smile. In case you didn’t know already goldfish do have some redeeming qualities, and they may be cause to consider them again as a new family pet.
  • There was an interesting article I read this week on the renewed interest of creating biotopes. I have always found the idea of setting up and maintaining a biotope interesting, and with all the new technology and advances in the aquarium world this is a better idea than ever! Biotopes are displays that are more true to nature, a little slice of a specific habitat and conditions with only plants and animals that are native to that habitat. These setups are a lot of fun to watch, and are great to reproduce for keeping specific fish in a habitat as close as possible to the one they’re found in naturally. I’m hoping that we can create one or two as retail displays in the future.
  • Whitebanded Pygmy WrasseWe get questions all the time from customers about something that emerged from their live rock or from a coral or from seemingly nowhere. Strange worms are often a fact of life in reef aquaria, and though you may not always see them, chances are there are some hiding away in the dim recesses of your rock. This little gem might help you ID or at least get closer to IDing the little surprises that come along with reefing.
  • Lots of you have pretty strong opinions, like we do, on bill HR669. Frank gives a recap of what’s going on with it now over on the Reptile Blog.
  • The biggest news in the retail store this week is the new plant gravel in our plant room. The plant gravel has been furnished by Seachem and will not only improve the appearance of the space, but hopefully benefit the plants for their short time in the room. Check it out to see all the colors of the new substrate in action if you’re considering a substrate change or a new planted aquarium.
  • New and exciting this week at TFP:

    Check the blog for pics of these guys.

  • I get excited any time we get Oxycheilinus sp., Cheilinus sp., and other similar wrasses. These fish are often overlooked and washed out in our pale tanks but they are real gems in the home aquarium with tons of personality and flashy color too. Check out the Snooty wrasses (How you can you not love something with a name like Snooty?) in stock this week, and watch of other similar wrasses like the Twospot Wrasse and Floral Wrasses periodically.
  • Cave BassWe got a Cave Bass this week! These guys aren’t available often but they are super neat. They’ll tend to hide out in shadowy caves in your tank, but you’ll be pleased just to know he’s there.
  • This little beauty, the White-banded Pygmy Wrasse, only gets to be about 2 inches long. A-dorable, and safe for the reef. Think nano reef or biotope!
  • People don’t often get excited about tunicates. Generally they look like a lump of putty or nothing much at all when they arrive, but the blue tunicate that arrived this week is quite a looker!
  • On the freshwater side, these Spotted Pike Characins are pretty eye catching. Not community friendly, but nice for the right tank!
  • African Oddities – the Bichirs and Reedfish

    Hello, Frank Indiviglio here. I have always favored fishes that seem to straddle the line between the fish and reptile/amphibian kingdoms. Included among these are both marine and freshwater forms, including the toadfish, frogfish, lizardfish, lungfish, mudskipper (note the common names!) and others. The freshwater fish family Polypteridae, containing the bichirs and the reed or rope fish, has long fascinated me and seems very popular with visitors to the exhibits I have worked on at the Maritime Aquarium (Norwalk, CT) and the Bronx Zoo.

    Few if any bichirs have been well-studied, and even the most commonly available species are rarely bred in captivity; much can be learned by the patient aquarist.


    The dorsal fin rays of these elongated, snake-like fishes are separated from one another, rising and falling in a series of humps and lending them the appearance of scaled-down dragons. This effect is most evident in the aptly named Senegal dragonfish (please see below). The pectoral fins are rimmed with fleshy lobes, and are paddle-like in shape and function.

    Swimming takes the form of short bursts, but mainly these fish scull along the bottom. The largest, including the commonly sold reedfish, can reach 3 ½ feet in length, but most are considerably smaller. Although dissimilar externally, bichirs are believed related to sturgeons, paddlefishes and gars.

    Range and Habitat

    Bichirs are limited in range to tropical Africa and the Nile River system, and are usually associated with shallow, plant-choked waters such as marshes, swamps and the shores of slow-moving rivers.

    Future Amphibians?

    The amphibian-like qualities of the bichirs are not limited to appearance alone. The swim bladder has evolved into an accessory breathing organ, allowing them to breathe atmospheric oxygen and to survive out of water for some time…few species are rumored to voluntarily leave the water for short periods. The young of some species even sport external gills, much like salamander larvae!

    Reed or Rope Fish, Erpetoichelys calabaricus

    This brown West African native has a sinuous, snake-like body and a wide mouth. The reedfish hides under the mud by day, emerging at night to feed upon insects, fishes, worms and frogs. It can reach a length of 3 ½ feet, but rarely attains that in captivity.

    Senegal Dragonfish or Cuvier’s Bichir, Polypterus senegalus

    Rounded, widely-separated dorsal fin rays lend the Senegal dragonfish an uncanny resemblance to its mythical namesake…it really does look like a miniature dragon!

    Senegal dragonfishes are distributed throughout the Congo Basin and reach 12 inches in length. They make hardy, interesting aquarium pets and often learn to anticipate feeding times. The effect of a large specimen in a well-planted aquarium is quite spectacular – they definitely deserve more attention from aquarists.

    Ornate Bichir, Polypterus ornatipinnis

    Swamps and marshes in West Africa are the home of this commonly imported bichir. Patterned with a lacework of black markings, the ornate bichir is one of the more attractive members of its family.

    Unfortunately, due to its unique appearance, the ornate bichir is often purchased on a whim. Few realize that the youngsters sold in pet stores eventually grow to 18 inches in length, and are often aggressive towards tank mates. However, properly accommodated ornate bichirs make fascinating pets, and, as they are rarely bred in captivity, are ideal species to study.

    Further Reading

    You can read more about bichirs, and see a list of all recognized species, at

    I’ll address captive care in more detail in the future. Until then, please write in with your questions and comments. Thanks, until next time, Frank Indiviglio.

    Polypterus senegalus image referenced from Wikipedia and originally posted by Zhyla

    Rope fish image referenced from Wikipedia and originally posted by Michael Zalewski

    Aquarium Fish Growth Myths

    Eileen here. Some myths and legends are universal. Almost every country has some version of a “bigfoot” legend. Nessie is one of Scotland’s biggest celebrities. People are abducted by aliens and UFO’s are spotted in the sky around the world. What does the aquarium hobby contribute to this list?


    “Fish only grow to the size of their aquarium.”

    Like most of those other stories, this one likely started because people saw some truth behind it. They saw their fish grow large in relation to their aquarium, stop growing, then die. But, just like we now know that the Earth is not flat and we will not fall off the edge of it if we sail too far, we now know that the size of an aquarium does not dictate the size of a healthy adult fish.

    The most common victim of this theory is the  comet goldfish, the fish often sold as very inexpensive feeder fish or won in carnival ping-pong ball toss games. People win the fish or buy them as inexpensive pets, not knowing that the tiny fish they took home should be able to become an 8-10 inch adult with a lifespan of 10 years or more if well cared for. “Goldfish bowls” are sold almost everywhere that carries fish supplies. Small aquariums – 10 gallons or under – are often sold with pictures of small fancy goldfish on the box so it is no wonder that people may be unaware of the problems they are walking into.

    Keeping any animal, fish or otherwise, in a habitat that is too small for it causes a number of problems that might not be obvious at first. The fish people win at carnivals or purchase as small juveniles might be fine for a short time in a small aquarium, but as the fish grows, so does its requirements. Looking at the same situation in terms of a person instead of a fish, it becomes more obvious. An infant, for example, doesn’t require much space for his needs to be met. He can feed and exercise within the area of his nursery and regular cleanings can keep his nursery healthy. But, as the infant grows into a toddler, his needs also grow. He requires more space to exercise so his muscles develop properly. He is growing and needs more food and so produces more waste as a result that the same regular cleanings the infant received cannot control. As he grows through his life, that boy can certainly grow into a man if never let out of the nursery that he was kept in as an infant, but that man will not be as healthy as he could be. His hygiene and development will have suffered from being kept in a confined space and not allowed to flourish and develop properly and he will probably not live as long as a man whose environment has been allowed to grow with him.

    The same happens when a fish is kept in a small tank. As the body of the fish grows, so does the amount of waste it produces and the food it needs. This can affect the water quality of the aquarium and lead to disease caused by high ammonia levels, high nitrite levels, low dissolved oxygen content, low pH and other incorrect parameters. Just as a person kept in a small space cannot grow properly, the fish would also physically not be able to grow to its full size. Its body and skeletal structure may be stunted by the lack of space and ability to exercise and swim as it should, but the internal organs often continue to grow at a normal rate. The internal damage this causes, in combination with water quality issues, will lead to a premature death.

    While a small tank can certainly affect the size of the fish, it is not the way that we once believed. There is no internal sensor in a fish that can detect the size of its environment and adjust its growth accordingly. The fish we keep are  just as dependent upon us as small children to give them the proper care needed to keep them healthy so it is up to us to be aware of what their needs are and to do our best to make sure those needs are met throughout the fish’s life.