Big Fishes Eat Little Fishes.  That’s their job.  They do it for a living.  When you mix lunkers with small fry, you wind up with plump lunkers.  Some fishes’ mouths are surprisingly large – especially the bettas.  They’re great at making neons disappear. 

Pick Your Favorite.  Start with the fish you like best and work from there.  However, certain fishes belong in almost every tank.

Livebearers Multiply Fast.  Livebearing fishes breed very rapidly:

1. Guppies every four weeks

2. Moons and Swords every six weeks

3. Mollies every eight weeks

Most baby livebearers get eaten long before you see them.  If you want to enlarge your livebearer population, put your pregnant momma fish in a plant-filled aquarium.  Feed her well.  You’ll save half the babies.  They have surprisingly large spawns – frequently over 50 babies at a time.  Some momma gups will pop out 100+.

Livebearers add color, food, variety, sex, and population to your tank.  Most get along well with other fishes.  However, most like to pick at the slime coating on goldfishes.  Some may also pester angels and gouramis.

Guppy males sport fancy tails in a variety of colors.  They’ve come a long way from the non-descript wild ones we used to see years ago.  Take a look at the feeder guppies to appreciate the contrast.

Swords Like to Jump.  Keep swords in covered tanks.  They’re the worst jumpers.  Keep your swords and other livebearers in trios – one male to two females.  Both sexes will be happier.

Moons Add Color.  You can’t go wrong with “moons.”  They get their name from the crescent shape on the tails of many color varieties.  They’re also called platies – a contraction of their former Latin name -- platypoecilius.  Add lots of moons for a rainbow of colors.

Schoolers Stick Together.  Tetras, barbs, and danios travel in schools.  They eat, reproduce, and swim in groups.  In the wild their schooling behavior gives them protection and security.  The more you keep of each kind, the better they feel.  Add zebras for action and neon tetras for color.

Barbs Surprise You.  Since barbs range from about two to twelve inches, you usually need advice on which ones to add.  Leave tinfoils out of your 10-gallon tanks.  You can usually find a half-dozen or so barbs with good colors that top out under three inches.

Cichlids Need Room.  Bigger egglayers, such as Central and South American cichlids, keep best as pairs or single specimens.  Most cichlids – especially African cichlids – should not be mixed with regular community fishes.  They like to beat up and/or eat other fishes.  Most cichlids are territorial and claim lots of elbow room.  African cichlids keep best when crowded.

Angels, kribensis, and rams are a few “cichlid exceptions” that work well in regular tanks.  Always add angels for dignity and variety.  Provide breeding/hiding caves for the other guys.

Catfish Belong.  Every tank needs a collection of cats on the cleanup crew.  Small and medium tanks need corydoras cats.  They come in a variety of color patterns and rarely exceed 2 ½ inches.

For the tiniest tanks, the tiny Corydoras hastatus grows only a little over an inch long.  All corys eat particles of food that fall to the bottom of their tanks.  They root through the gravel with their whiskers in search of miniature missed morsels.  

Larger tanks also need catfishes.  There are dozens and dozens of intriguing catfishes available.

Plecostomus Eat Algae.  Plecos and other sucker-mouthed armored catfish eat the algae that grows on the sides of your tank.  Most tanks need at least one algae-eating fish -- AFTER the green algae starts growing.  This may take an extra month or more to grow.  Plecos housed in new bare tanks quite frequently starve to death.

Plecos eat at night – long after the other fishes have totally devoured their rations.  Put in a tiny pinch of food right before you turn off the lights, or feed sinking pellets to the plecos.  Plecos come in several species, sizes, and prices.  In the same category, we also include farlowella cats, whiptail cats, Borneo suckers, and otocinclus cats.

We do not recommend the so-called Chinese algae eater because it doesn’t like to eat algae after it gets a few mouthfuls of tastier fish food.  Many prefer to suck hickies on their tank mates.  Big ones get surprisingly mean.  We do recommend the Siamese algae eating sharks and the algae eating shrimps

Some Loaches Look Like Worms.  Loaches include a large group of wiggly, worm-like fishes.  Their sensitive whiskers and ability to burrow through the gravel on the bottom make them great additions to the clean up crew.  Then there's the humpy-back loaches -- some get meaner than fish five times their size.  We strongly recommend clown loaches once your tank stabilizes.

Snails are Useful.  Snails are eating machines – 24-hour-a-day eating machines.  You can grossly overfeed a tank containing snails and never even know it.  They work great in tanks with small fishes and no copper or clown loaches.

Mystery snails are one of the big guys of the snail crowd.  They are hard to breed.  The little pesky snails that multiply like crazy usually come in as hitch hikers on plants.  Snails other than mystery snails reproduce amazingly fast.  A clown loach will take care of them.  Big cichlids even eat the shells.

Bettas Are Beautiful.  They love to fight each other so one per tank please.  Put a mirror in front of them to entice them to “flare” their fins.  They love to show off to the mirror.  Make sure you feed them betta pellets, brine shrimp, or other foods for picky eaters often.  Most don’t like flake foods very much.

Most Gouramis Mix.  Gouramis are a colorful but larger peace-loving cousin of the bettas.  They come in a variety of colors and sizes – from an inch long to two-feet long.  Most grow to about three to five inches.

Goldfish Are Tough.  Goldfishes fill a very special niche.  More people start with goldfish bowls than any other fish.  Most inexpensive comets get fed to larger fishes.  In outdoor pools they grow into foot-long specimens.

Little fantails carry beautiful fins -- especially viewed from the top.  They come in several colors.  Fancy show specimens from Japan sell for larger sums of cash.  Even small ones cost much more than U.S. goldfishes.

We would classify all goldfishes as good eaters.  Resist the temptation to feed them too much.  Keep them away from nippy fishes like tiger barbs.  Lots of fishes like picking at goldfishes fins.  One female guppy in a goldfish tank keeps them all jumping as she nips away at them.  Goldfish do best when kept with other goldfishes.