How can I ensure my fish live long, happy lives?

May 31, 2009 11:47 AM

What size tank and type of fish are best for a beginner with a ~20 tank size limit? I'd like something that isn't too time-consuming.

I've googled it and seen this, but the former results vary wildly and the latter is mostly for larger tanks.

1) What size tank would you recommend for a beginner? It's for a dorm room with a ~20 gallon limit.

2) What type of fish are happiest in this size tank? I'm going for freshwater.

3) I've read that you need to fill the tank and let it sit for a week, and I've read that you don't need to do that. Which one is it?

posted by biochemist to pets & animals (12 comments total)

The only advice that I have (I have never kept fish, but my father has for YEARS) is that larger tanks are more forgiving of errors while trying to maintain the water chemistry.
posted by frwagon at 11:52 AM on May 31

Larger tanks are easier, and establishing a tank in a dorm room is more difficult (there is a lot more dust floating around, scuzzing things up)
posted by Think_Long at 11:54 AM on May 31

What frwagon and Think_Long say is absolutely true, so if your limit is 20 gallons, don't get anything smaller than that. If you can stretch it to 25 or 29 gallons, even better.

You will be faced with the choice of "long" or "tall" tank (both of these come in 20 gallon sizes). A tall tank is more aesthetically pleasing to some, and its stand will have a smaller footprint. However, for beginners I recommend a long tank; they are easier to keep clean, have a greater surface area (which translates to more fish while maintaining a healthy environment), and provide more room for lateral swimming, which means you can be more flexible in the types of fish you choose.

For types of fish, I recommend picking one type that you are most interested in as the "centerpiece" of your tank, then choosing others according to their compatibility with your main species. Spend some time watching different fish in the store and think about whether you like the idea of fish swimming to and fro in peaceful schools, or if you prefer somewhat more aggressive types with their own "personalities."

If you prefer schooling fish, anything in the tetra or danio families would be good to start out with; you could even have two schools (different varieties) as long as you don't overcrowd. Gouramis might be a good choice if you like the idea of slightly more aggressive fish, as they can be somewhat territorial with each other but generally ignore other species (I've kept gouramis and danios in the same tank without any problems, so this can be a way to have the best of both worlds). I don't recommend highly aggressive fish such as cichlids for a beginner, and most of these are too large for a 20gal tank anyway.

The "aggressive," "semi-aggressive" and "community" labels you see at the large chain stores are often insufficient indications of what fish can be safely mixed. Once you've decided on your main species, your best bet is to go to a locally-owed fish store where there are experienced fish keepers who can advise you on what can safely be kept with it.

You should indeed fill your tank, plug in the power filter, and introduce "seed bacteria" for at least a week (keep the light on during the day). This is called cycling, and it greatly reduces the odds of new fish dying because it gives the tank's biosystem a chance to build up essential bacteria before adding the fish. I use Stability to introduce these bacteria, but some people simply "feed" a new (fishless) tank by dropping in a few flakes of fish food every day while it cycles, and this seems to work well enough.

Keeping an aquarium can be an immensely rewarding hobby and never fails to impress guests. Good luck!
posted by [user was fined for this post] at 12:59 PM on May 31 [1 favorite has favorites]

1) 20 gallons is OK for beginners. Don't even think about getting a smaller tank.

2) I suggest buying small (when fully grown) fish that are compatible with each other and with your tank conditions. Read, read, and read some more while your tank cycles (see 3) and then buy no more fish than your tank can accommodate.

3) Read about "fishless cycling" and buy a "master test kit" (forget about those test strips) to monitor your water chemistry. It's the humane (and much easier) way to cycle your tank. It should take less than a month to cycle and, while waiting, you'll have plenty of time to learn more about your future pets.
posted by shinybeast at 1:07 PM on May 31 [1 favorite has favorites]

Try not to get anything that is too aggressive, to start with. And stay away from the fancy guppies if you can, I know the ones we've been getting at my pet store have all been sickly and inbred, for the entire time I've worked there.

Actually, try to avoid chain store fish at all. I know that the filter system in my store is connected to ALL the tanks, so if one fish is sick it can spread to the whole system. Apparently UV sterilizers and the size of the system are supposed to stop that from happening, but in my experience, if one tank gets fin rot, at least two others do as well.

If you can find a locally-owned fish store, or someone that is an aspiring fish breeder to buy from, you're probably better off going that route.
Good luck!
posted by d13t_p3ps1 at 1:53 PM on May 31

Anecdotal warning: In high school, I maintained a five-gallon fish tank for a while after its owner abandoned it. She was a clueless owner — the tank was much too small for the three fish inside. It took more work than I expected (messy, somewhat smelly work) to change the water, check the chemistry, adjust the chemistry, clean the tank, etc. I also had to worry about how to take care of them when I went away for a weekend; I don't know what you'd do during spring break (or similar).
posted by dreamyshade at 1:57 PM on May 31

Aquaria Central has a great forum for beginners. They have great information on fishless cycling, adding fish, compatibility and every other question you might have.

Definitely do fishless cycling. It's the way to go.

In addition to the size of your tank, think about water chemistry. Do you know what kind of water chemistry you will have in your dorm? Some fish are very sensitive to pH, others can tolerate a wide range. In my experience fish can often tolerate a steady pH that might be slightly outside their standard comfort zone, but they really don't do well with wildly fluctuating pH. So figure out what pH your water will stabilize at and choose fish that will be happy in it. You can change the pH with buffers that you add to the water, but this is an enormous pain in the butt and requires constant vigilance, and I'd recommend against it for a beginner.

My beginning fish were dwarf gouramis and zebra danios. And you'll want an algae-eater to keep the green stuff under control. Be sure you know how big your algae eater will grow, so that you don't wind up with a tankbuster. For this reason I am partial to otocinclus for algae eating; they do fine in smaller tanks than many plecostomus do.
posted by ambrosia at 1:58 PM on May 31

I started with a 20 gallon (80 liters) tank & two goldfish, who can have great personality and started the tank off without fish for almost a month.

As suggested I also started with no fish in the tank for the first month except for a plant from a tank that had fish in it - the plant will come with biological's that help kick start the proper chemistry, and you don't just have a big jar of circulating water on your desk. If you go to a good fish store they will help you get all the chemistry you need - expect to spend at least 40$ on water conditioner (mine's 10$ for a big tub) ~8 for biological booster, decent testing kit - mine was ~15. You may need to adjust the PH - the local folks will know what's up. You'll also need a bucket and for a twenty gallon I would get at least a 2.5 gallon - remember you'll be doing water changes pretty often.

The chemistry is relatively straight forward: PH should be around 7.4, some fish like it a little higher.

Ammonia & Nitrite are the big fish killers in a new tank - both are waste products. Ammonia you can quickly deal with by frequent water changes - at least 1/2 the water once a month.

The nitrite is converted by the biological filter into nitrate and this bio filter takes time to get working. The first time fish are in your tank change the water like frequently - my last new tank I was changing weekly. Nitrate is my enemy because the tap water here also has nitrate - so it's an issue even after changing the water. I am considering filtering all the water & am trying to deal with it chemically.

Goldfish require a bit more work as they produce more ammonia & nitrite but I like them - I have a black moor (has protruding eyes) and lion chu (no dorsal fin).
posted by zenon at 2:22 PM on May 31

I've kept tanks all the way from 10 gallons to 75 gallons (all freshwater) and the easiest tank ever has be the 40-gallon long. It's also, for me, been the most versatile, as sometimes it's hard to keep enough fish in the 75 for it to look interesting. So, yes, bigger is better, up to a point. The 20-gallon I had for a while was about as small as I'd care to go, but it was fine.

It might be overkill for a 20-gallon, but for big tanks, a Python No-Spill siphon that attaches to a faucet is the best way to keep them clean. For smaller tanks, a simple siphon like these works well. If you have an undergravel filter will keep the fish poo contained until you can vacuum it up with one of these. Keep the tank out of direct sunlight to prevent extreme algae growth, get a plecostomus to eat most of the rest, and have a teflon toilet scrubber dedicated to the tank. When you do remove water, remember that frequent, small changes of water are best.

Zebra Danios are impossible to kill. Slightly more difficult, but still quite easy, are most varieties of tetras. Both of these are peaceful. I especially like lemon tetras and serpae tetras for any size tank. They do best in a small school, so for a 20-gal, I'd get at least 6 of the same kind.
posted by zinfandel at 2:44 PM on May 31

20 gallons is the minimum I'd recommend for a beginner. Anything smaller is a lot less forgiving.

Avoid goldfish - people seem to think that they are great first fish, but they produce a lot of waste for their size, requiring a lot more upkeep. They also grow fairly large, which limits the diversity you can have in your tank.

Livebearers are fun, because you get to see the baby fish being born. Livebearers include mollies, platies and swordtails. I usually buy them in threes - one male for every two females. If your fish store person can't tell the difference, go to another fish store! It's pretty easy.

As others have said, cycle your tank before adding any fish.

Live plants are a great addition, especially if you get mollies. They like to eat plants.

A couple corydoras catfish are great for cleaning up the bottom of the tank.

Avoid dyed fish - that's just mean. If the name of the fish at the pet store includes the words "blueberry," "strawberry," "creamsicle," or "day-glo" chances are that it's been dyed.

posted by Ostara at 2:47 PM on May 31

Maybe off topic, but - seriously - Don't do this to the fish. You're going to have to vacate over breaks, and possibly move out over the summer. If you have room mates, they're going to do (to them) cute things that probably wind up at the very least stressing them badly ('Here fishy fishy!' tap-tap), if not killing them outright. ("How was I supposed to know the plastic would poison them?").

It's a great hobby, and they're wonderful creatures - but if you've never kept fish, you really aught to hold off until you've got your own space, where you don't have to worry about things like tank leaks.
posted by Orb2069 at 9:47 PM on May 31

Seconding Orb2069. Its a time intensive, messy and smelly hobby that I would be wary of starting in a dorm room. The max I'd go for is a decorative beta in a small, unfiltered bowl in a dorm, but even that is a hassle when you go on break.
posted by slateyness at 12:02 AM on June 1