Aquariums Archives - Gray Rock Pets

Zebra danios (Danio rerio) will always hold a special place in my heart because they were the first fish I ever kept. While most people start out in the aquarium hobby by squishing a huge goldfish into a tiny fishbowl, I jumped straight into the deep end and bought a 5-gallon tank to fill with a school of fish. In hindsight, it was lucky I chose zebra danios, as they’re an incredibly hardy species that were barely fazed by my numerous early mistakes. And that’s what makes them such a great beginner fish—they’re incredibly difficult to screw up with.

Zebra Danio Stats

Minimum Tank Size: 5 Gallon (10 Gallon Recommended)

Care Level: Very Easy

Water Conditions: pH 6.5-7.2 and Soft to Medium Hard

Temperature: 65-77 °F (18-25 °C)

Maximum Size: 2.5 inches (6 cm)

In the old days, many aquarium books even recommended cycling aquariums using zebra danios. While the ammonia and nitrites would kill many other delicate fish (I’m looking at your neon tetras), the zebra danios usually emerged from cycling completely unscathed. Of course, we know now that fishless cycling is far superior, but it just goes to show how tolerant they are of poor water conditions.

But zebra danio toughness isn’t the only reason to own them. They are also an attractive fish, with interesting behaviours, and are happy eating just about any fish food. Once introduced to an aquarium, they will establish a pecking order, with the larger fish often claiming a territory. It’s always fun to watch them interact, though you’ll need at least six of the fish to experience this behavior (which also happens to be the minimum number recommended for an aquarium.)

Natural Habitat

Zebra danios are found throughout India and Nepal and are currently listed as Least Concern by the IUCN Red List. This means that while their population is declining—possibly due to the aquarium trade—they are not currently threatened.

In their natural habitat, they are found in streams, ponds, canals, ditches, and rice paddies. They prefer slow moving and even stagnant water, and the water is often choked with vegetation. In areas without any aquatic plants, they will often congregate near areas with overhanging plants.

Housing

If you’re going to keep zebra danios, then I always recommend using at least a 10-gallon aquarium. While many sites claim you can get away with using a 5 gallon tank, it’s really too small, and you’ll inevitably end up with water quality issues.

A zebra danio’s aquarium should have a sand or gravel substrate (aquarium grade only), and also plenty of aquarium plants to reduce stress. The plants have the added benefit of helping to filter the water and are often a godsend in a new tank. Decorations and driftwood can also be added, but just make sure they don’t have any jagged edges that can tear a fish’s fin. Also, make sure you leave enough open space, as zebra danios are very active and clear need areas for swimming.

Once your aquarium has been cycled, the plants have been added, and there’s a little bubbling treasure chest on the bottom (not actually required), then it’s time to add the zebra danios. You shouldn’t add them all at once, but in groups of threes to prevent any spikes in ammonia or nitrites. It’s important to monitor the water quality after adding new fish, and if you don’t want to buy a testing kit, you can usually get the water tested for free at a local pet store.

Feeding

One of the things I like the most about zebra danio is the ease of feeding them. While some fish like dwarf puffers make you want to tear your hair out as they spit out yet another new food, zebra danios will accept almost anything you offer to them.

In the wild, they feed on tiny crustaceans, worms, and insect larva. If you really want to make your fish happy—or you’re conditioning them for breeding—zebra danios should be a similar diet to what they eat in their natural habitat. Some easy to find live foods are gut loaded brine shrimp, black worms, copepods, and daphnia. Of course, they’re perfectly happy accepting any store-bought fish foods, but it’s a good idea to supplement their diet with frozen foods like blood worms, blackworms, and brine shrimp.

I recommend feeding zebra danios two-three times a day, and all the food should be gone after two minutes. If any food remains after that time, then you’re overfeeding them. And if you’re overfeeding then, you’re going to end up with algae and water quality issues.

Breeding

Zebra danios are incredibly easy to breed, but they will need a separate breeding tank if you want to raise the fry. While they will regularly scatter their eggs in an aquarium—usually following a water change, which tricks them into thinking the monsoon breeding season has arrived—they are notorious for eating their own eggs. If they’re kept in a community tank, it’s incredibly rare for any of their offspring to survive.

If you’re ready to try your hand at breeding zebra danios, then the first thing you need to do is set up a breeding tank. The dedicated aquarium should be fully cycled (this is incredibly important as newborn fish are very sensitive to water fluctuations) and empty except for a single layer of marbles at the bottom. The eggs will fall through the spaces between the marbles and keep them away from the hungry adults.

Once the breeding tank is ready, you should separate the male and female zebra danios into their own tanks. The females will have rounder and plump bodies, while the males will be more streamlined. After they’ve been placed in separate aquariums—within sight of each other—they should be fed high-quality food for at least a week. After a week has passed, the females should have plumped noticeably as their bodies begin to swell with eggs.

I usually wait until the next morning to add a pair of the zebra danios to the spawning tank. Then I leave them in until the next morning. Hopefully, they will have spawned by then, and you can usually tell by the female becoming noticeably thinner. But if it looks like the female didn’t scatter any eggs, then you can simply repeat with another pair until breeding occurs.

Tank Mates

I find zebra danios to be one of the best community fish in the hobby. They are tough enough to defend themselves against other fish, but generally leave even the most docile fish alone. That being said, fish with long flowing fins like guppies should be avoided, as zebra danios occasionally nip. Also, they will eat live-bearer fry, so unless you want to use them for population control, avoid them in molly and platy tanks.

Some of the best tank mates for zebra danios are corydoras catfish, tetras, rasboras, and many of the smaller barbs. They also do well with most loaches—even the large ones like weather loaches—and pleco fish.

The guppy (Poecilia reticulate), with its long flowing tail and spectacular colors, is probably one of the most easily recognizable fish in the aquarium hobby. And when you combine its striking appearance with its ease of care and peaceful nature, it’s easy to see why these fish are so popular.

Origin

Guppies were one of the earliest fish kept in aquariums, and they were first collected in Venezuela in 1859. When the specimens reached the British Museum of Natural History in 1861, they were given the name Girardinus guppii. Later, the name was shortened to guppy by aquarium enthusiasts, and eventually the fish came to have several names, including rainbow fish, red-tail fish, millions fish, and many others.

Characteristics
Care Level: Easy
Temperament: Peaceful
Life Span: 2 Years
Maximum Size: 2 Inches (6.5 Centimeters)
Minimum Tank Size: 5 Gallons (18 Litres)
Temperature: 65-80°F (18-27°C)

Habitat

Guppies are native to Venezuela, Brazil, Guyana, and several Caribbean islands, including Trinidad and Tobago, Barbados, Jamaica, Netherlands Antilles, and the United States Virgin Islands.

However, they have since been introduced across the globe—often in the hopes of keeping mosquito populations down—and have since become one of the most widespread fresh-water fish. Unfortunately, their introduction has had a negative impact on native species, and they’re now considered an invasive species in many countries.

Guppies can adapt to most habitats, and are found in streams, ponds, rivers, and lakes throughout their native range. Some can live in brackish water, but those are rare. Guppies prefer slow moving and shallow water and tend to avoid fast currents.

Guppy Aquarium Setup

The minimum aquarium size for guppies is 5 gallons (37 liters), but this is only if its going to be a male-only aquarium. If the tank is going to have mixed sexes, then a 10-gallon aquarium should be provided, though larger tanks are easier to maintain.

If your aquarium is going to house both males and females, then there should be a ratio of at least two females to every male. Guppy males will constantly attempt to breed with any females in their aquarium, and by having more females, it should limit the attention any one fish receives.

If there aren’t enough females to spread out the attention, then they may become stressed and ill from the constant harassment.

When setting up the aquarium, plenty of live plants should be included, along with decorations like driftwood and river stones. However, anything with sharp edges should be avoided as it can damage the guppies’ delicate tails.

It’s important to remember when setting up the aquarium, that an open swimming area should be left for the fish. As for the substrate, sand or aquarium gravel with muted colors are both excellent choices—but once again, just be sure to avoid anything jagged or sharp.

Filter

Guppies are one of the few fish where a sponge filter might be the best choice for filtration. Because of the remarkable speed of their breeding, guppy tanks are often filled with tiny fry. And while hang-on-back and canister filters will both suck the young up to their deaths, sponge filters are completely safe for the fry.

But if you don’t want to use a sponge filter, then a hang-on-back filter can still be used, but a cover should be placed over the intake (either mesh or sponge) to prevent the fry from being sucked up to their doom.

Guppy Feeding

In the wild, guppies are omnivores, though they primarily feed on algae. But they will also consume any tiny invertebrates and detritus they find while browsing for food near the bottom of the waters they inhabit.

Since nearly all the guppies for sale are captive bred, they will readily accept fish food without issue. But they should also regularly be fed lightly blanched vegetables and live or frozen foods. Some of their favorites are daphnia, blackworms, bloodworms, and brine shrimp.

Guppy Breeding

There’s an old joke among fish keepers that to breed guppies just add water. And there’s some truth to that joke. Unlike many other fish in the aquarium hobby, there are no taxing requirements to trigger breeding, and if a male and female guppy are kept together, eventually, they will produce fry.

But as previously stated, it’s important to maintain the right ratio of sexes in their tank. There should always be more females than males, and a good ratio is around 1:3, though 1:2 will still work.

To determine the sex of a guppy, simply examine their tail. The males will have long colorful tails, while the females will have short tails with muted colors.

If you want to get into more advanced identification methods, then you can look at the anal fins—the males have a narrow modified anal fin called a gonopodium—while the females have a triangular anal fin.

Another easy way to sex the females is to look for a dark area directly behind the anal fin, which is called a gravid spot.

While guppies will breed in community tanks, the survival rate of fry may be low as other fish will eat them. If you’re looking to breed guppies, then a dedicated breeding tank should be set up.

Any tank being used to breed guppies should be fully cycled, and it’s recommended to include floating plants and dense plants like Java moss. Not only does the infusoria (tiny freshwater life forms) living on the plants provide additional food sources for the fry, but the hanging roots and dense stems also act as good hiding places from hungry adult fish.

Until you’re ready to begin breeding, the males and females should be kept separately. Once you’re ready to start, then a single male and female should be placed in the tank for approximately 24 hours.

After that, the male should be removed while the female is kept alone in the breeding tank. After around 28 days, the female will give birth, at which point she should also be removed to keep the fry safe. While guppies aren’t as notorious as other fish for eating their young, new parents may still consume them.

Newborn guppies have fully developed mouths and they can eat ground up fish food immediately. However, some breeders choose to use baby brine shrimp instead or the commercially available fry food to increase the fry’s growth rate.

At around the four week mark, the male and female fry should be separated to prevent them from breeding with each other.

Guppy Tank Mates

While guppies are an excellent addition to most community tanks, they often do best in a species only aquarium. One reason for this is that their long fins often become targets for nipping, and their peaceful nature allows them to be easily bullied.

However, there are still some fish and invertebrates that coexist well with guppies. These include most corydoras catfish, kuhli loaches, bristlenose plecos, harlequin rasboras, neon tetras, otocinclus catfish, snails, and shrimp.

Zebra Danios: The Complete Care Guide