Dark Knight Rams/Black Rams – Keeping, Feeding & Breeding

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I don’t think anyone would deny that Rams are some of the most colorful fish in the hobby. German Blue Rams are like a rainbow of color, Gold Rams look amazing and Electric Blue Rams stand out from the other side of the room.

The Dark Knight Ram, which is also called the Black Ram, is simply stunning. How they have managed to develop a black fish that seems to be full of color is just beyond my comprehension.

Overview of Dark Knight Rams

Dark Knight Rams are a manmade color strain of the ever-popular German Blue Ram. The Dark Knight Rams were developed by Danziger Discus Farms in Tel Aviv, Israel following many, many years of selective breeding.

Since their development and the hype generated by many popular fish-keeping YouTubers, the Dark Knight Ram was one of the most highly anticipated new arrivals to the hobby in living memory.

Other color forms of the Dark Knight Ram include the regular German Blue Ram, the Gold Ram, and the Electric Blue Ram.

Whilst the Dark Knight Ram does not exist as a color form in the wild, much of the following information is based on the original fish, the German Blue Ram.

Dark Knight Ram Characteristics

Common Name:Dark Knight Ram, Black Ram, Midnight Ram
Scientific Name:Mikrogeophagus ramirezi
Origin:Venezuela and Colombia (although a manmade strain)
Tank Distribution:Lower regions
Adult Size:2.5″ to 3″ (6cm to 7.5cm)
Life Expectancy:3 to 5 years
Care Level:Beginner to Intermediate
Minimum Tank Size:20-gallons (75 liters)
Breeding Method:Egg layer
Temperature:84°F – 86°F (29°C – 30°C)
pH:5.0 – 7.0
Hardness:18 – 179 ppm

Dark Knight Rams Origins

Dark Knight Ram Origin Map

Dark Knight Ram Habitat

Clearly, the Dark Knight Ram doesn’t have a natural habitat as such, but essentially the German Blue Rams’ habitat is the same.

The Ram originates from the Orinoco River basin in Venezuela and Colombia. The river system itself is vast and covers a huge area of northern South America.

If Dark Kight Rams were in the wild, they would be in slower flowing sections of the rivers as well as flooded areas of forest.


Are Dark Kight Rams Wild Caught or Captive Bred?

All Dark Knight Rams are captive-bred. The color form doesn’t exist in the wild.

Dark Knight Rams are the result of a long, expensive breeding project carried out by Danziger Discus Farms in Tel Aviv, Israel. They started to cross-breed dark color forms of the German Blue Ram, and once they realized there were some black traits, they selectively bred the best specimens until they developed the Dark Knight Ram.

Dark Knight Ram Description

Dark Knight Rams, as their other common names, Black Rams and Midnight Rams, suggest, are very dark to black in color.

Dark Knight Rams grow to around 2.5″ to 3″ (6cm to 7.5cm) in length and the majority of their bodies are colored from dark purple to black, depending on the quality of the strain.

Their fins still have the characteristic orange color of regular German Blue Rams, and some individuals still show the blue spots.

Are Dark Knight Rams Aggressive?

I have been keeping regular German Blue Rams for many years, and the only time I have found them to be aggressive is when they are spawning. A spawning German Blue Ram will defend his brood against much larger fish.

Dark Knight Rams in my care have certainly proven to be a lot more aggressive. I wouldn’t class them as aggressive fish, and I would keep them with the same tank mates as other Ram color morphs, but there is no doubt they have a little more aggression in them.

I suspect the extra aggression is the result of the color strain being produced from a relatively small gene pool.

Dark Knight Ram Tank Setup

In my experience, Dark Knight Rams work equally well whether you keep them in a small tank like a 20-gallon (78 liters) or as part of a much larger setup.

I recently kept a group of Dark Knight Rams in a 55-gallon (210 liters) tank with a pair of Angelfish. It was a heavily planted tank and the Dark Knight Rams looked stunning.

Dark Knight Ram Tank Size

I have found that a 20-gallon (78 liters) tank is ideal for a pair of Dark Knight Rams, even if they are a breeding pair. If you were hoping to keep a bigger group, maybe 4 or 5 Dark Knight Rams together, I would consider keeping them in a 30-gallon (113 liters) tank.

As with any fish, the more you plan to keep, the larger the tank should be, and like any other fish, the larger the tank you give your Dark Knight Rams, the more stable the water parameters will be.

Dark Knight Ram Substrate

The Dark Knight Rams scientific name is Mikrogeophagus which comes from the Greek (mikrós), meaning ‘small’, and Geophagus meaning ‘earth eater’.

Rams have this scientific name due to their propensity to continually dig through the substrate looking for small fragments of food to eat. Knowing that Dark Knight Rams want to dig through the substrate, we should give them a suitable substrate.

In my experience of keeping these fish, I would always recommend using a sand substrate like this one which I usually just order from Amazon.

Plants in a Dark Knight Ram tank

Over the years I have come to really appreciate a heavily planted tank, and I think there can be no doubt that all color forms of Rams look amazing, and behave more naturally when they are living in a planted tank.

If you are new to plants, I have a great article on the best aquarium plants for beginners.

In my own Dark Knight Ram tanks, I grow the following plants, all of which are hardy and do well providing you give them a decent light and the occasional addition of fertilizer.

I like to use some of the taller plants towards the back, such as the Vallisneria or Amazon Sword, then short plants towards the front of the tank. I find it gives a real sense of perspective and helps make the tank look deeper.

Decorations in a Dark Knight Ram tank

For me, recreating a fish’s natural habitat makes for the best tank visually. However, I don’t think the Dark Knight Rams themselves really care what decorations you use.

I like to use pieces of aquarium-safe wood and roots as well as some larger rocks to try to recreate a natural habitat. I wouldn’t call it a biotope, but it certainly feels natural.

If you want to use a ceramic castle or a SpongeBob Pineapple House, then it will be fine.

Dark Knight Ram

Filtering a Dark Knight Ram tank

The type of filter you use doesn’t really matter, providing it keeps the Dark Knight Rams water clean and clear. These fish like their water to be stable, and a poor quality filter can lead to an unexpected ammonia spike.

I have had good luck using hang-on-back filters on almost all of my Ram tanks. Hang-on-back filters are easy to service, fairly cheap to buy, and they keep the aquarium clean without blowing the fish all over the place.

Heating a Dark Knight Ram tank

The number one secret I would happily share with all Ram keepers, no matter what color form, is they like their tanks hot! The major reason people find Rams fall apart and die on them is that they do not keep their tanks warm enough.

Dark Knight Rams want their water temperature to be around 84°F – 86°F (29°C – 30°C).

I have started to convert my own fish room over to the E-Series heaters which are made by Fluval. They are a little more expensive than regular aquarium heaters (check the current price here), but I have found them to be very reliable and I love the digital display on the front, which tells me the current temperature of my aquarium.

Lighting a Dark Knight Ram tank

Although these fish are naturally a very dark color, they have surprisingly bright spots and other markings when the light hits them at the right angle. As such, having a good light will make your Dark Knight Rams look spectacular.

Any good aquarium light will do the job, but I have found the Aquasky light to be really good.

Dark Knight Ram Water Parameters

The Dark Knight Rams parent fish, the Geman Blue Ram, originates in slower flowing waterways that have soft, warm waters which are slightly acidic. To get the best out of your Dark Knight Rams we should try to recreate those conditions wherever possible.

  • Temperature: 84°F – 86°F (29°C – 30°C)
  • pH: 5.0 – 7.0
  • Hardness: 18 – 179 ppm

If you are unsure of your aquarium water parameters, invest in a good quality water test kit. I currently use the API Master Test Kit as it measures pH, Ammonia, Nitrite, and Nitrate. I have found it to be the most accurate test kit for the money. You can check the current price of the API Master Test Kit on Amazon.com here.

What Do Dark Knight Rams Eat?

Dark Knight Rams are omnivores. This means they will happily eat both meaty foods like worms and crustaceans as well as vegetation like small pieces of plants and bits of algae.

As mentioned above, Dark Knight Rams spend a fair amount of time sifting through the substrate looking for food. Their natural choice is to eat either from the bottom of the tank or in the lower regions as the food falls through the water column.

My own Dark Knight Rams eat a lot of the following fish foods;

  • Vibra Bites
  • Bug Bites
  • Xtreme Krill Flakes
  • Hikari Micro Wafers

As well as feeding my Dark Knight Rams commercially available dried fish foods, I also try and give them as much live and frozen foods as I can. I like to feed my Dark Knight Rams the following;

  • Daphnia
  • Mosquito Larvae
  • Bloodworms
  • Brine Shrimp
  • Cyclops

How Often Should You Feed Dark Knight Rams?

Over the years, I have found feeding my fish little and often is better for the fish than feeding them one large meal a day. I try to feed my Dark Knight Rams 3 or 4 times a day.

My daily feeding routine looks something like this;

In the morning I feed my Dark Knight Rams a sinking pellet. That usually means either Bug Bites or Vibra Bites. In the afternoon I feed flake food. My go-to at the moment is Xtreme Krill Flake as it really enhances their color. In the evening I offer live or frozen food, depending on what I have available. Finally, in the evening, if my schedule allows, I will feed pellets for a second time.

I believe feeding little and often is better for the fish’s digestive system, and better for my filter as the fish’s waste is spread out through the day.

One final advantage I have found in feeding my fish little and often is it gives me more opportunities to interact with my tank, and every time I interact with my tank, I have the chance to spot any problems with my fish or the tank equipment.

How To Breed Dark Knight Rams

Dark Knight Rams are an excellent choice of fish to breed for someone who has dabbled in fish breeding but now wants to move on to a fish that will prove to be more of a challenge.

Dark Knight Rams can be a little tricky to breed, and they don’t always breed true (meaning not all their offspring will share their coloration), but once you master breeding them, they can be both rewarding and profitable.

Dark Knight Rams are egg layers. Like so many other members of the Cichlid family, they are very good parents. Both the male and female Dark Knight Rams will guard the eggs and the subsequent developing baby fish.

Before they will spawn, Dark Knight Rams need to pair off. It is possible to introduce a male and female Dark Knight Ram together and they will form a pair and spawn, but they will never form a strong pair bond. Instead, a group of Dark Knight Rams should be kept together, and pairs should be allowed to form naturally.

Dark Knight Rams that form their own pairs often form strong pairs that will raise many generations of baby Rams.

Sexing Dark Knight Rams

It is possible to tell male from female Dark Night Rams just by looking at them, but it does take a little knowledge and a bit of practice to get it right. Be aware that the more Dark Knight Rams you have to look at at any one time, the greater the chances you can tell a male from a female.

Generally speaking, male Dark Knight Rams will have more color than females (although really high-quality Dark Knight Rams can be almost completely black). Also, the first 2 or 3 dorsal rays on the male Dark Knight Rams tend to be elongated. Female Dark Knight Rams are usually plumper in the body than males, especially when they swell with eggs as spawning time nears.

The best way to be 100% sure which sex your Dark Knight Rams are is to wait until a pair forms and spawn, then see which of the fish lays the eggs and which one comes along behind her fertilizing the eggs.

Conditioning Dark Knight Rams

To get the best possible breeding performance from our Dark Knight Rams, we need to make sure they themselves are in the best of health. We call this process conditioning.

In my experience of breeding Dark Knight Rams, the best way to condition them is to feed them lots of live or frozen foods. When getting my pairs ready to spawn, I will feed them live or frozen food at every meal for two to three weeks.

Live blackworms are possible the best food for conditioning Dark Knight Rams to spawn.

Dark Knight Ram Spawning Tank Setup

I have had pairs of Dark Night Rams form and subsequently spawn in the community tank, and this is fine if they are kept with fairly placid tank mates. However, the chances of producing a brood of baby Dark Knight Rams are increased massively if the fish are spawned in a dedicated breeding tank.

I have found a 10-gallon (38 liters) tank to be the ideal size for spawning a single pair of Dark Knight Rams.

The spawning tank doesn’t need to be elaborate. I like to leave the bottom of the tank clear, but a sandy substrate can also be used. Decoration in the tank should be limited to a couple of flat stones for the fish to breed on, plus one or two plants or rocks to provide line-of-sight blocks should the female want to get away from the male.

A small sponge filter will usually be sufficient for a Dark Knight Ram spawning tank (I have had great success using this sponge filter as it doesn’t require a separate air pump) and a heater to keep the water warm enough.

Dark Knight Rams Spawning

You will know your pair of Dark Knight Rams are preparing to spawn when both fish begin actively cleaning the rock they want to lay their eggs on. They will meticulously clean off any algae or debris from the rock using their mouths.

Once the chosen spawning site has been cleaned to their satisfaction, the female will begin passing over the rock in straight lines, depositing eggs as she goes. The male will then follow behind her fertilizing each row of eggs. They will continue to do this until 300 to 500 eggs have been laid and fertilized.

Once spawning is over, both parents will stand guard of the eggs, fighting off all other fish that come too close.

Whilst Dark Knight Rams make excellent parents, it is not unusual for them to take a few tries to get good at it. I have known pairs eat the first 3 or 4 spawns before suddenly deciding they should try raising the babies rather than eating them.

German Blue Ram guarding eggs

Dark Knight Ram eggs usually hatch within 2 to 3 days, largely depending on water temperature. After hatching they will spend another 3 or 4 days as wigglers (essentially tiny wiggling fish that can’t swim). Wigglers feed of their eggs sacks which will still be attached.

Once the fry become free-swimming the parents will continue to guard them and may move them two or three times over the coming days, always trying to keep the cloud of baby fish between the two parents.

Dark Knight Rams continue to look after their fry for 5 to 6 weeks, after which time the parents may be ready to spawn again.

German Blue Ram with fry

Raising Baby Dark Knight Ram

If like me, you want to raise as many Dark Knight Ram babies as possible, you might want to consider removing the baby fish from the parents and raising them yourself.

The real skill in breeding Dark Knight Rams is raising the fry to full-grown adults. Baby Dark Knight Rams are around half the size of Angelfish babies.

The first food I feed my Dark Knight Ram babies is always First Bites, which is made by Hikari (see more about First Bites). Hard-boiled egg yolks also work really well. I will feed them First Bites for around 3 to 4 days after the fish become free-swimming.

After 3 or 4 days of eating First Bites, I will transition my baby Dark Knight Rams on to freshly hatched brine shrimp. Freshly hatched brine shrimp is one of the most nutritious foods you can give any baby fish.

I will continue to feed my babies freshly hatched brine shrimp for about 6 weeks before slowly moving them over to crushed flake food.

Other Ram Color Morphs Available

As mentioned at the beginning of this article, Dark Knight Rams are not a natural strain of fish, rather they are a color morph of the German Blue Ram. They were produced by some very talented breeders.

Below I have shown the natural form of the German Blue Ram, and some of the other color strains available in the hobby.

German Blue Ram

German Blue Ram

German Blue Rams are one of the most colorful fish in the freshwater fish-keeping hobby. They are extremely popular and can be found for sale in almost every local fish store around the world.

Electric Blue Rams

Electric Blue Rams

Electric Blue Rams are one of the oldest color morphs of the German Blue Ram and have been in the hobby for many years. As their name suggests, the Electric Blue Ram is primarily bright blue in color with a yellow to gold patch on their heads.

Gold Rams

Gold Rams

Gold Rams are essentially half gold and half white. Gold Rams have been popular, especially in the Far East, for many years. In my experience, Gold Rams are a little less hardy than regular German Blue Rams.

Dark Knight Ram Tank Mates

Dark Knight Rams make a great addition to the community aquarium, providing their tank mates are chosen wisely. Many of the tank mates for Dark Knight Rams are the same as any of the other color morphs of Rams.

Over the years I have kept many different species of fish with my Dark Knight Rams and below I have listed some of my favorites.

  • Dwarf Gouramis
  • Mascara Barbs
  • Neon Tetras
  • Silver Tip Tetras
  • Rosy Barbs
  • Bristlenose Plecos
  • Pygmy Corydoras
  • Pearl Gouramis

Dwarf Gouramis

Dwarf Gouramis

Dwarf Gouramis bring a real punch of color to the Dark Knight Ram aquarium. These peaceful fish spend much of their time in the upper regions of the tank, well away from the Dark Knight Rams.

Mascara Barbs

Mascara Barb

I genuinely believe more people should keep Mascara Barbs. Unlike their more nippy cousins, the Tiger Barb, Mascara Barbs are peaceful, free-swimming fish that bring color and movement to any tank you keep them in.

I currently keep a group of 8 Mascara Barbs with some of my Dark Knight Rams, and it is a tank that I never get bored of watching.

Neon Tetras

Neon Tetras

These small, colorful, active fish bring real movement to a Dark Knight Ram aquarium. Their bright blue and red colors bring out the best in the Dark Knight Rams colors and the Neon Tetras will pose no threat to the Dark Knight Rams, even if the Rams happen to spawn in the tank.

I have hundreds of Neon Tetras in my fish room, spread across multiple tanks. It is easy to see why Neon Tetras are one of the world’s most widely kept fish.

Silver Tip Tetras

Silver Tip Tetras

Silver Tip Tetras are one of the tightest schooling fish in the freshwater fish-keeping hobby. A group of them schooling back and forth across the tank never get boring to watch.

Silver Tip Tetras are a mid-water species of fish that will take little to no interest in the daily business of your Dark Knight Rams.

Rosy Barbs

Rosy Barbs

Rosy Barbs are another peaceful member of the Barb family. Assuming you keep them in a group of 6 or more, they won’t show any signs of aggression or fin nipping towards your Dark Knight Rams.

Rosy Barbs bring lots of color and movement to your aquarium. They are continually on the go and contrast the Dark Knight Rams both in the color and activity levels.

Bristlenose Plecos

Bristlenose Pleco

I don’t think there is a fish in the hobby I preach about more than the humble
Bristlenose Pleco. I believe this hard-working fish should feature in every community tank set up across the country.

Bristlenose Plecos are peaceful and will keep your tank almost completely clear of algae. They will also quickly scavenge any uneaten food that makes it to the aquarium floor.

Pygmy Corydoras

Pygmy Corydoras

Anyone who has kept Corydoras catfish knows they like to spend their time bumbling along the bottom of the tank. The reason I suggest keeping Pygmy Corydoras with your Dark Knight Rams is that the Pygmy Corydoras likes to spend much of their day swimming up in the open water, away from the Dark Knight Rams.

Pygmy Corydoras are peaceful and will go about their day, not bothering the Dark Knight Rams. This is especially important should your Rams decide to spawn in the community tank.

Pearl Gourami

Pearl Gourami

I think Pearl Gouramis are really underrated in the hobby, and it always surprises me I don’t see more people keeping them. Pearl Gouramis spend the vast majority of their day at the surface, well away from the Dark Knight Rams. The two species of fish will rarely interact.

At first glance, Pearl Gouramis don’t appear to bring much color to the tank, however, when the light hits them at the right angle, their pearl-like coloration which gives them their common name is simply stunning.

Dark Knight Ram Tank Mates To Avoid

Whilst there are many different fish to choose from that make great tank mates, there is also a list of fish I would recommend avoiding. Clearly, this could be a very long list, so I will spare you the obvious candidates.

Large and aggressive South American Cichlids such as Oscars, Green Terrors, and Chocolate Cichlids should be avoided, as should some of the small Cichlids like Convict Cichlids and Firemouth Cichlids as they will readily spawn in the aquarium, creating a hostile environment.

African Cichlids also make a poor choice of tank mates. Clown Loaches are not always a good choice of tank mates either as they usually want to occupy the same spaces as the Dark Knight Rams.

Common Dark Knight Ram Pests and Diseases

Whilst I would class Dark Knight Rams as fairly hardy are robust, they can be prone to a couple of different diseases, especially when they become stressed due to unruly tank mates or water temperatures that are too low.

The most likely pests or diseases to affect Dark Knight Rams are;

  • Ich (whitespot)
  • Fin Rot
  • Internal Tapeworms
  • Dropsy


In my experience, Ich, (which is usually referred to as Whitespot in Europe), is probably the most prevalent disease in the hobby.

Ich is characterized by the white spots that usually start on the fish’s tail and fins before spreading across the whole body. Left untreated, the Ich can overwhelm and kill a fish surprisingly quickly.

The spots are in fact not spots, but rather cysts that form when the Ich parasite burrows under the fish’s scales.

After spending over 30 years keeping and breeding fish I have come up against Ich many times. The best treatment I have found is Ich-X which is made by Hikari. Ich-X can only defeat the parasite when the parasite is free-floating in the water, not when it is buried beneath the fish’s scales, so repeated treatments may be required.

Fin Rot

Fin rot is the result of a bacterial infection that literally eats away at the infected fish’s fins and tail. The fins start off with small pieces missing at the edges. Left untreated, fin rot will eat away the fish’s fins and tail, leading to the death of the fish.

The most common cause of fin rot is poor water quality. When we allow our water quality to deteriorate, bacteria can become present in large numbers. This bacteria then tasks advantage of a fish that has been fin nipped or injured itself another way.

Fin rot is both preventable and treatable, providing treatment comes swiftly.

There are a number of good treatments for fin rot on the market. One of the best is Maracyn (see more about Maracyn on the Aquarium Coop website). If you are in Europe, eSHa 2000 is a really effective treatment for bacterial infections.

Internal Tapworms

Internal tapeworms are extremely common, especially in newly imported fish. Fish that eat from the substrate, like Dark Knight Rams, are especially prone to internal tapeworms due to the way the tapeworm reproduce.

Tapeworms live inside the Dark Knight Rams digestive system, consuming the goodness from the Rams food before the Rams can. A Dark Knight Ram that is heavily infested with tapeworms can actually starve to death even though they eat every day.

Tapeworms can quickly spread through a tank of fish, so treatment is essential. I have found Paracleanse, which is made by Fritz, to be the most effective treatment for internal parasites.


Dropsy isn’t really a disease, rather it is the name given to a fish that swells up as a result of fluid build-up inside the fish’s body cavity, usually as a result of kidney failure or bacterial infection.

Dropsy is notoriously difficult to treat and the prognoses for any fish is poor. Euthanasia is often the kindest thing for a fish.

My Final Thoughts on Dark Knight Rams

Dark Knight Rams are certainly the new kid on the block when it comes to the Dwarf Cichlid family. They are still relatively hard to come by and highly sought after by many hobbyists.

If you fancy keeping something different, and the thought of breeding these intriguing fish appeals to you, I would certainly say go for it. In my opinion, a well-planted tank with a group of Dark Knight Rams swimming around is a tank you won’t ever get bored of watching.

About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James