Fungus – the ever present danger to fish and eggs

This golden julie from lake tanganyika has fungus

Fungus – the ever present danger – to fish and eggs

This golden julie from lake tanganyika has fungus
This golden julie from lake tanganyika has fungus

There are many species of aquatic fungus but by far the most common two are saprolegnia and achlya.

Symptoms of fungal attack

Fungus occurs as white, grey and sometimes brown fluffy growths on the skin or fins of fish or on developing eggs from a spawning.

Saltwater fish actually suffer less, than freshwater fish, from fungus because of the salt in a marine environment. However, brackish water fish, even mollies, when kept in insufficiently salty water are the most prone to fungal attacks.

Fungus often starts as a small tuft, and usually spreads when not treated and can kill a fish if the fungus penetrates the internals of the fish. Fish eggs if not treated or infected eggs are not removed can cause all nearby eggs to be infected and killed.

What causes fungus to develop

Fungus and fungal spores thrive in damp environments with decaying organic matter and an aquarium is full of water so is ripe for fungal outbreaks. Fungus sprouts where there is decaying organic matter, dead fish, or unfertilised or dead fish eggs. When fungus grows it releases millions of spores into the water which will quickly infect any fish that has a break in its protective mucous which may occur after rough handling or an attack from another fish or bumping into aquarium rocks.

Parasitic diseases such as ich, body ulcers and infections will damage the protective mucous and allow entry of fungal spores, compounding the fish’s problems.
When fish are kept in poor quality water conditions with water that is full of bacteria, nitrites, ammonia and excessive fish waste then they are much more likely to get infected by fungus.

Fungus treatment for fish eggs

Several eggs from this spawn are starting to get infected
Several eggs from this spawn are starting to get infected

With fish eggs any unfertilised eggs or dead eggs will quickly get infected with fungus. If that egg is not quickly removed then the fungus will spread and infect otherwise healthy eggs. All adjacent eggs may be killed.

Prevention of egg infection by fungus is achieved by adding methylene blue to the water immediately after the eggs have been spawned. Be careful not to overdose because eggs may suffer developmental problems. Also remove any off-white eggs with a pipette before they become heavily infected.

Cichlids actually do a good job in removing dead and unfertilised eggs and keeping the eggs free from dirt as part of their parental care.

Fungus treatment for fish

Treat as soon as possible. use an aquatic antifungal remedy from your local aquarium shop. Place any heavily infected fish in a quarantine tank and treat the fish there. In the main aquarium a dose of salt added to the water should heal slightly infected fish and help to kill of most spores present.

Prevention is better than cure and this is a mostly preventable illness. Remedy the environment of the aquarium that led to the original outbreak. If it was an accident such as a dead fish then a salt dose to the aquarium should be sufficient.

However, if the cause was rotten food then you must keep up good feeding practices of not feeding more than the fish will eat. Observe all the food you place into the aquarium and remove any uneaten food with a siphon. When your aquarium has a nitrite or an ammonia spike then fish will go off their food. If you feed at this time then you will surely cause a disaster.

Make sure your filter is fully cycled. Make sure that the water you add to the aquarium has the chlorine removed before adding. Also, siphon through and disturb the gravel to remove any build up of fish waste. And make sure your filter has not become clogged. If the filter is clogged then squeeze out the excess dirt from the sponge into a bucket of aquarium water.

And finally, keep up good maintenance practices. Then you should never have a problem with fungus again.

 

Breeding egg laying fish

fish laying eggs
Angel fish laying eggs

Fish laying eggs?

Many times fish keepers are caught by surprise and your fish may have already laid eggs. If you are lucky enough to have a male and female that have bred in the aquarium then you most probably want the eggs to hatch to become baby fish. This may be difficult if the fish lay eggs in a community aquarium. If the fish are cichlids they will look after their eggs and young to some extent. Remember other fish will want to eat the eggs and baby fish if they get a chance. If you want to maximise your chance of raising the baby fish then it might be a good idea if you carefully removed the other fish. Note that disturbing fish with eggs or young may result in the parents killing their offspring.

Fish such as angel fish, kribensis, or convict cichlids are the most likely to spawn with out ay help from you. And as often as not they will spawn in the community aquarium.

More about Kribensis here
 
Breeding fish A-Z

How To Start Breeding Egg-Laying Fish: A Guide To Egg-Layers

convict cichlid breeding pair
breeding pair of convict cichlids

If you have already enjoyed some success breeding livebearers such as guppies or platys then your next step could be breeding egg-laying fish. These fish can be a bit more of a challenge in producing healthy young successfully, but are well worth the effort.

With the success of breeding live-bearing fish, you should already have most of the equipment and expertise necessary to make the step up to breeding egg-laying fish. So how do you complete the next step? What do you need to know and do? You need to provide the right water conditions and the appropriate spawning environment for the adult fish. Then you need to feed and raise the young which are usually smaller than livebearer fry.

Choosing Your First Egg-Layers

breeding group of zebra danios
breeding group of zebra danios

There are many egg-laying fish species that breed in one of several ways. In order to maximize your chances of success, it is recommended that your first egg-layer be either a simple cave-spawner such as kribensis or convict cichlids, or easily cared for egg-scatterers such as zebra danio or rosy barb.

Egg-laying fish that protect their young are relatively easy to spawn plus they look after their eggs and fry: The optimal conditions can be reached by raising the water a few degrees, feeding well with live food such as blood worms, and providing a cave-like structure or spawning stones somewhere in the tank.

Kribensis, for example, will seek out a cave or other similar hiding place when ready to spawn. The female will lay her eggs in the cave and let the male fertilize them. For the next week or so, they will both guard the nest from other fish.

Setting Up The Right Conditions For Egg-Layer Spawning

female_kribensis_fish_with_fryThe first thing to take into consideration for breeding egg-laying fish will be to set up the correct temperature for spawning. Every species of fish has different needs, but there are a few universal principles that will apply to keep the eggs and fry safe; one of these is the use of a separate breeding tank.

Fish eggs and fry are largely considered fair game for hungry adult fish—including the parents of some species. For this reason, you will need to setup a breeding tank in order to prevent other fish eating the fry. Also a breeding tank has space for your fry to grow.

Another overlooked danger for eggs and fry is your filtration system. Eggs and fry are so tiny that they can easily be sucked into the filter where they will be crushed. Your breeding tank will need to use a low flow sponge filter in order to keep the eggs safe at least for the first week or two.

In the case of egg-scattering fish such as the Zebra Danio, it is recommended that both adults are removed immediately after laying is complete. Installing a layer of marbles or a porous net as a substrate can help protect the the eggs which will fall between the gaps where they cannot be reached or eaten.

Successfully breeding egg-laying fish also requires more attention to the water quality and feeding. Clean tank water encourages breeding, and often the most difficult part of breeding is maintaining the correct balance between high quality water and high levels of food. Many fish will only breed when given very clean water and live food.

How to recognise if your fish are breeding

zebra danio fish
femal zebra danio fish

When the female is noticeably plump and the male is more vibrantly coloured then you can be sure the fish will soon spawn. With brood carers such as kribensis and convict cichlids you will notice mouth wrestling between the pair. Also they will flirt with each other by waving their bodies and fins at each other. With egg scatterers you will see flirting and chasing. When the fish spawn they usually quiver their bodies as they lay eggs and release milt.

Caring For Your Fish Eggs And Raising Fry

If you have managed to get your fish to breed, and have a number of fish eggs waiting to hatch in your breeding tank, it is time to focus on keeping them safe until hatching and then providing the fry with everything they need to grow into healthy adult fish.

Once your eggs are safely deposited in the breeding tank and out of reach of any other fish, you are ready to begin the waiting game. With very clean water and an appropriate temperature, you should begin to see fry appear within a few days or so.

However, do not feed the fry when they first hatch. They will not feed. And are not yet free swimming but just dart about occasionally. Fry when first hatched still have a yolk sac attached which they feed off. When they have completely absorbed the yolk sac, they will then start eating and start free swimming. They need to be fed at this point. This is where most beginners fail.

three week old zebra danio fry
three week old zebra danio fry

When breeding egg-laying fish, it is often necessary to feed your fry live food—the problem here, however, is that many of these fish are too small to eat many commercially available live foods. The best foods for these tiny fry are infusoria, which have to be cultivated beforehand. After a week or two depending on species they will be big enough to eat baby brine shrimp and microworms. After 1 month they can then be fed on crushed dry food.

In order to encourage the growth of your fry, frequent feeding and water changes are recommended: Your fry should be fed lightly several times per day, and at least 10% of the water changed every other day.

More about live food here

Considerations For Fish Nearing Adulthood

If your first experiment in breeding egg-laying fish has gone well so far, you should have a small breeding tank full of young fry that are rapidly growing. But you will soon have to make space for the young adult fish to move into.

If you have a breeding tank of 50 litres that is housing perhaps a 100 young fry, you will not be able to keep them all there for very long. If you already have a network of contacts to whom you can sell your or swap your young fish, then you should be able to sell them off relatively quickly, but it is important to have extra tank space ready just in case. If needs must then you can try offloading some at your local petstore.

If you have prepared a separate tank for the adults to live in, you will be able to successfully transfer them there when they are adults and begin selling them off without pressure. Nobody wants to spoil all of this hard work at the last step because there is no room for an otherwise successful attempt at breeding egg-laying fish.