Starting A Marine Aquarium

Starting A Marine Aquarium

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Hints and Tips On Starting With Marine Fish

Whether you see them in your local aquarium store or public aquaria, on a diving holiday, on TV, or more recently at the movies an aquarium housing some of these outstanding creatures would make a welcome addition to the homes of many people. However it is very demanding and quite expensive to look after these wonderful animals properly. Beginner fishkeepers really should get used to looking after tropical freshwater fish or goldfish first before moving onto marine fishkeeping. However for aquarists with fishkeeping experience a marine aquarium is a stunning and rewarding addition to their home.

The principle reason marine fish are so much more of a challenge to keep than their freshwater cousins is to do with the complexity and stability of the seawater they live in.

Because the sea is such a vast body of water its characteristics hardly change at all, so marine fish are far less forgiving of changes in the water quality than their freshwater relatives. So proper management and regular testing of the water is essential.

Another reason these creatures pose such a challenge is that many marine fish have very specific feeding requirements. For example many species of coral reef Angelfish feed only on certain species of sponges, Seahorses often feed readily, but are such poor swimmers that they need to be kept on their own or they cannot get to their food in time. Many types of marine invertebrate filter feed material out of the water and certain corals need light to allow algae in their tissues to grow.

Marine fish are considerably more expensive than most freshwater ornamental fish because most of them are caught from the wild .The costs involved in managing wild capture and transport of these fish makes them more expensive. However an increasing number of marine fish are being commercially bred leading to lower prices for fishkeepers.

marine fish aquariums


In order to look after marine fish the first thing we need is the correct water. Seawater is a very complex cocktail of many dissolved substances, and there are several varieties of synthetic seasalts available from your local aquatic shop, that can be added to water to make seawater. Making the correct strength of seawater is vital, and continually monitoring the salt strength is also essential. Changes in salt concentration will occur, most commonly due to evaporation.

Regular partial water changes are essential and whenever one is performed, which may need to be done every week in some tanks holding marine invertebrates,a new batch of seawater will need to be made up to replace that taken out.

What are the options?

There are many types of marine aquarium, some contain only fish, others may house a mixture of fish and invertebrates. A good ‘starter’ marine tank would hold hardy species such as Moray Eels or ‘Volitans’ lionfish. These fish are a little more forgiving if the water quality becomes slightly less than perfect. However both are carnivores, moray eels can deliver a nasty bite and lionfish a dangerous sting.

There are many other species of fish available for a fish only marine aquarium. Speak to your local aquarium store for details .The usual rules of fishkeeping apply of not keeping predators with smaller tank mates and expect aggressive behaviour from many marine aquarium fish including species of Triggerfish and Tangs. Even tiny damselfish can be very aggressive if a much larger fish strays into their territory.

A fish only aquarium is a great way to begin marine fishkeeping with different fish available to suit smaller tanks to a huge aquaria.
There are many types of invertebrate available for the marine aquarium. There is a staggering diversity of corals and anemones, starfish and sea urchins, tubeworms and ‘feather dusters’ shrimps and crabs.

All of them are simply beautiful creatures but are very demanding to look after. They are intolerant of poor water quality and often have very specific feeding and in some cases lighting requirements.

Perhaps the pinnacle of the marine aquarium world is the mixed fish and invertebrate aquarium often called a ‘reef’ aquarium.The challenge here is finding the correct balance between invertebrates and fish numbers and species.

But beware – many species of fish regard the invertebrates that were carefully selected and lovingly cared for, as a tasty meal. Whether you opt for fish only, inverts only or a mixed system, always read up on your chosen animals and plan carefully to avoid problems with aggression or predation. Remember small fish may become huge tank busters, and small fish can have large territories

marine fish

Basic equipment

There is a massive array of equipment available to run a marine aquarium, with reef tanks having vast banks of equipment needed to maintain good water quality. For a simple marine aquarium there are a few essential pieces of equipment:

Always aim to get the largest tank you can. The greater the body of water in the tank the more stable the water quality. Also you can then accommodate more livestock. The minimum tank size for a marine aquarium is 100 L, anything less cannot provide stable water quality.
A filter is an essential piece of equipment as this processes the waste from the fish and keeps the water healthy and clear. Fish only systems have more basic filtration needs whereas ‘reef’ aquaria need very complicated external filters or ‘live-rock’ filtration. Speak to your local aquatic store for advice. Make sure you get a filter suitable for your tank, as this is the life-support system for your fish and invertebrates.

Most marine aquaria have a protein skimmer installed. This very useful piece of kit uses minute air bubbles to strip fish wastes out of the water and helps the filter to keep the water healthy and clear. There are many types available and they are an incredibly useful addition to the vast majority of marine aquaria.
Fish only systems need lighting sufficient to illuminate the tank and see the fish. Very bright lights may make some fish timid, ‘Moon – lights’ are available which simulate night time allowing you to watch nocturnal activities of your marine tank.

Reef aquaria have very specific lighting needs.This is due to many corals, anemones, clams and others, having minute algae in their tissues that they need to feed and grow. The algae is a plant and thus needs light to photosynthesize food. Speak to your local aquatic shop staff for more details on lighting requirements of your livestock.

Looking after marine fish

Before starting your marine aquarium it is essential to research the feeding requirements and behaviour of your planned livestock. There are some essential questions to ask:

Will a fish eat its tank mates or invertebrates?

Example - Lionfish and frogfish can consume tank mates only slightly smaller than themselves! Many butterfly fish will eat the invertebrates in a reef tank.

Can you provide the food your livestock needs, remember some marine fish have very specific feeding needs?

Example – many marine Angels and Butterfly fish have very specific feeding needs which the average aquarist can not supply.

Can the fish compete for food in the tank?

Example – seahorses are poor swimmers and are rarely fast enough to get to food when kept with other fish

How big does the fish grow?

Example – A twin spot wrasse grows from a small spotted fish of 5 - 8 cm (2 - 3 inches) into a monster that outgrows most home aquaria.

Is the fish aggressive?

Example – triggerfish are renowned for their aggressive behaviour Stocking densities of marine fish are lower than for freshwater aquaria.A marine tank can hold 20 - 30 cm body length (excluding tail) of slender bodied fish per 100 L of water. For deeper bodied fish that figure may drop to 10 cm of body length (excluding tail).

marine reef tank

Looking after marine fish

Once the aquarium is established its day to day maintenance is similar to a freshwater aquarium. Herbivorous marine fish may need feeding 2-3 times a day, or seahorse aquaria may need a regular supply of live food , carnivores may be fed around twice a week. The most important piece of maintenance on any aquarium is a regular partial water change. In marine aquaria is especially imperative as the livestock is so intolerant of poor water quality. A water change of 10 –20 % total volume should be performed for invertebrate systems. For fish only systems 10 - 20% fortnightly is reasonable. Regular testing of the water quality is also essential as the water can become unhealthy very quickly if new fish are added, too much food is added or a piece of equipment like a pump stops running. When exposed to poor water quality the fish becomes stressed making them more vulnerable to dangerous diseases.

When looking after a marine aquarium it is essential to test the following water quality values each week:

Specific gravity (Salt concentration) Ideal value = 35 grams of seasalt per litre
pH ideal value 8.1 - 8.3
Temperature 24 - 28 °C
Ammonia Ideal value = zero
Nitrite Ideal value = zero
Nitrate Ideal value = zero for aquaria housing invertebrates for fish only aquaria a maximum reading of 50 mg / L

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Tetra Marine Advice

Tetra Marine Advice

Types of marine aquarium Many people start with a fish-only aquarium, as these tend to be the easiest to care for. This is because the fish are less demanding than corals and other invertebrates....(click on product image for more details)