Here’s Why Captive-Bred Seahorses Die (10 Causes)

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Out in the wild seahorses have quite a low survival rate since they are almost defenseless and any threat can totally consume them.

You would expect captive-bred seahorses to live significantly longer but even with them being protected within a closed system they still seem to die so often.

What are the causes and how can we increase the survival rate of captive-bred seahorses?

With many seahorse breeders surfacing it’s easy to get your hands on some captive-bred seahorses and many hobbyists are jumping in to grab them.

With this beginner frenzy, we see many mistakes and mishaps occurring resulting in dead seahorses, therefore I’ve compiled a list of the most common causes of death in captive-bred seahorses.

1. Poor Water Quality.

Poor water quality is probably the most common reason for seahorse deaths. Seahorses are very sensitive and they can pick up on any water irregularities.

An imbalance in anything can alter the specific water parameters they require. This is the root of most of the issues and sadly this soon leads to death. Some of the critical water parameters include

Oxygen Levels: Seahorses need high levels of dissolved oxygen in order to thrive. In an aquarium oxygen levels are not constant since the oxygen-holding capability is changing due to temperature and gravity.

Most oxygen-related issues occur at night since oxygen is used faster leaving the water with high levels of co2.

In an aquarium where the dissolved oxygen levels are low and/or the carbon dioxide levels are high, seahorses will exhibit very rapid respiration.

This soon causes death if left untreated.

Ammonia/Nitrite/Nitrate Levels: Seahorses, excrete ammonia as a waste product. However, ammonia is extremely toxic to them.

Fortunately, there is a group of beneficial bacteria that can convert ammonia into nitrites, but nitrites are also toxic.

The good news is there is a second group of microbes that can convert nitrites into nitrates, which are not nearly as toxic. Accumulated nitrates should ideally be kept below 10 ppm.

Balancing these chemicals is key in a seahorse tank if not, things go downhill from there.

PH Levels: Ph is very important for the well-being of seahorses they require a pH range of (8.1-8.4) to solidify water parameters in a saltwater tank.

Salinity/Specific gravity: Specific Gravity represents the amount of dissolved salt in the water. Standard guidelines are varied, but most saltwater aquarists have it at somewhere between 1.020-1.025 which is tolerated fairly well by seahorses.

Circulation: Circulation in a tank is extremely important in preventing dead spots. Having moderate to slightly higher water flow will help keep detritus from building up, and dissolved organics down, and allow the water to pass through filtration so it can do the work.

2. Bacterial Infections.

In an aquarium, there are bacteria mainly good bacteria and bad bacteria, pathogens for instance which are bad bacteria cause diseases.

These bacteria can cause a lot of health issues and even possible death in no time if treatment is not administered.

These deadly infections can feed off your seahorse’s flesh causing necrosis and possible death.

Most of the time these pathogens remain dormant in the water or in the seahorse waiting for weakness for them to attack.

When the seahorse’s immune system is compromised for whatever reason these pathogens replicate rapidly and they eventually overtake the host.

Such Infections include:

  • Vibrio bacterial infection.
  • Viral Hemorrhagic Septicemia.
  • Fungal Infections.
  • External gas bubble disease.

3. Stress.

Stress plays a big role in the health of seahorses, in fact, stress is one of the main killers in wild-caught and captive-bred seahorses.

Stress causes mental tension and difficulty which actually affects their overall health. Stress causes rapid respiration, affects hormones, and suppresses immune systems, leaving them prone to diseases.

As a result, seahorses may display abnormal swimming, and change in overall personality.

Stress can be caused by several factors within an aquarium. Such factors include Poor water quality, which is the most common stress factor.

Hobbyists must provide their seahorses with a stress-free environment with optimum water quality, and a nutritious diet.

They will thrive INCREASING THEIR LIFESPAN and your aquarium will flourish.

4. Poor Maintenance.

Many beginners always question the cost of running a saltwater aquarium for seahorses but they never really worry about the maintenance required.

Saltwater aquariums especially seahorse aquariums require proper maintenance in order to meet specific water parameters.

Seahorses are very messy eaters and this mess always ends up in the water affecting its quality.

Poor maintenance like skipping a weekly water change or forgetting to take water tests can endanger the life of your seahorse since they are very fragile and they need a suitable environment for survival.

Without proper management, seahorses will definitely not survive in an aquarium. Maintenance is the main reason for bad water quality which is one of the root causes of seahorse deaths.

5. Temperature.

The temperature within a saltwater aquarium is absolutely important, especially with seahorses who require specific temperatures for optimal health.

Seahorses are cold-blooded creatures, so their metabolic rate is determined largely by the water temperature they swim in.

Changes in water temperature can cause havoc in your seahorse tank, for instance, temperature changes can affect the following.

  • Oxygen-holding ability in water is affected by temperature since in water oxygen levels aren’t constant.
  • Seahorse respiratory rate, the warmer the water temperature, the higher their metabolism and the greater their oxygen demand becomes, and their breathing rate goes up accordingly. At lower water temperatures, the seahorse’s metabolism and oxygen demand are reduced, and their breathing rate slows.
  • Bacteria growth. Warmer temperatures of water will ignite bacterial growth allowing seahorses to be more prone to infections due to the increase in pathogens in the water.
  • Immune function is also dependent on water temperature. So when seahorses are kept at temperatures above their comfort zone, their immune system is compromised and they cannot fend off diseases.

6. Poor Feeding Habits.

Nutrition is big when it comes to the health of a seahorse and it’s very difficult to train them initially.

Captive-bred seahorses have adapted and are used to frozen foods but wild seahorses are not. If you have wild seahorses in your tank, I’m sure feeding is a problem since they require live food.

So if you feed your seahorse something they aren’t used to they will not eat. It’s preferable to always buy captive-bred seahorses who are already trained for certain food sources.

Another big issue is their diet, brine shrimp is a famously fed meal by many beginner hobbyists. While this food source is good it doesn’t serve as a full-course nutrient meal.

Also, brine shrimp water is high in ammonia and bacteria which can cause imbalances in your tank.

Frozen-washed mysis shrimp still remains the best meal for seahorses and it’s packed with the right nutrients for overall health.

Lastly, meal portions are also troublesome since overfeeding can be disastrous. Seahorses require the right amount of food per serving.

Any extra food beyond their appetites settles into the tank bed which rots and builds up bad bacteria which in turn causes imbalances in their overall saltwater system.

This opens the door to infections, a spike in bacteria levels, a spike in nitrates, etc. Death is rather certain in these cases.

7. Incorrect Tank Size.

There is a reason why seahorses require a big tank but many people seem to think because they are small they will do well in a small tank.

This however is a misconception that causes the death of many newbies seahorses.

Tank sizes dictate the water holding capacity and the more water the better. It’s advised that a pair of seahorses need at least a 30-gallon tank in order to thrive.

Bigger tanks with more water allow for more stable water parameters required by seahorses.

A spike in certain levels or a temperature change will take longer to affect a more significant amount of water than a small 10-gallon tank.

This creates some room for beginner’s error and this size of tank is more forgiving than the usual small tanks.

Bigger tanks also require less frequent maintenance since organic matter may take time to build up allowing you a little freedom for mistakes.

Another reason for tank sizes is the fact that seahorses are territorial. Overcrowding can cause them to stress and act out of character which leads to their deterioration.

The right size tank is crucial in keeping your seahorse happy within the right water parameters, if not water parameters will not be constant and their health will slowly deteriorate.

8. Parasites.

There are many parasites that attach to marine life whether they are from the wild or captive-bred.

Most parasites are often caused by poor quarantine and pre-treatment practices. Normally wildlife can harbor these types of parasites without any harm.

But when the health of the host is compromised these parasites have the chance to overtake.

These parasites can live for a long time remaining dormant and waiting for the right time. You may not notice your seahorse harboring parasites until they exhibit symptoms.

There are ectoparasites and endoparasites which can’t even be seen. Correct measures and treatment must be taken.

If not these parasites will gain power over their host totally destroying it in the process.

9. Tank Mate Predators.

Seahorses are very docile creatures and they are pretty much defenseless in comparison to other tank inmates.

They can be preyed on or injured by other tank mates who aren’t compatible with them. Most fishes and corals can’t be in a seahorse tank.

Fast-moving fish, aggressive marine life, and venomous corals are some of the inmates that aren’t compatible with seahorses.

They require tank mates of their own kind or other marine life that are similar to them. Compatible tankmates include starfish, snails, hermit crabs, gobies, etc.

It’s important to know that seahorses are bad swimmers and they can’t hide away from threats, they rely on their camouflage feature to remain in hiding.

These fish are sensitive and delicate and must be protected at all costs. They must be preserved in order to improve their lifespan.

10. Injury.

Seahorses are very delicate exoskeletal creatures with a thin layer of skin. They can be easily injured, scrapped, and broken to death.

Therefore their tank which serves as their safe haven must be properly thought of to make sure they are safeguarded from any possible threats.

Finding the right flow in a seahorse tank is also crucial. Because they are weak swimmers they rely on flow to move around. Strong flow can cause exhaustion and possible death.

That’s why most tanks have many powerheads to provide sufficient flow while keeping seahorses safe. however, powerheads can injure seahorses leaving them susceptible to infections.

Powerhead covers are required to protect seahorses from injury.

Another major threat is corals. Seahorses require hiding spots and corals are great for them to wrap their tails around.

Some corals are sharp, can sting, and are venomous. It’s important to find the right corals or even artificial ones to keep them satisfied yet protected.

The wrong corals can leave your seahorse, weak, infected, and immunosuppressed. With chances of possible death.

Carefully plan the layout of your seahorse tank, to make sure their needs are being provided for even if it means removing things that are bad for them.

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