One of most important moment, when you purchase one or more discus, is the acclimatization in the new aquarium or shop. Importance of this moment depends on the time of stay of fish into the bag. Even adverse environmental conditions, both in summer and in winter can expose the fish to the climatic fluctuations that negatively affect the already precarious living conditions inside the packaging.

First, it is very important to know what happen into the bag during transport.

It is generally a good idea that Discus are packaged individually, in this way fishes can not hurt themselves  against the rays of the fins of the others, and so they travel more quietly without the nervousness that can be transmitted to other subjects.  This also ensures that any other problem occurs inside the packaging is reported to a single subject.

The classic method of packaging is the bag that is filled to 1/3 with water and 2/3 with oxygen. It is a closed system that allows to fish to survive in good condition for 24-48 hours. If these conditions are good, the time spent inside the bag can be prolonged.

But what are the factors that alter these conditions? There are two types of factors outside and inside the closed system.

·     The external factors are: temperature and light.

An excessive rise in temperature causes an increase in fish metabolism causing a faster consumption of oxygen supply and an higher production of carbon dioxide. Also bacteria increases promoting the rapid reproduction of pathogens and not pathogens bacteria.

An excessive drop in temperature slows down the metabolism of the fish. This can compromise the immune system of fish, making it more susceptible to parasites that do not stop being aggressive even at low temperatures.

In both cases, an higher exposure time to "wrong" temperature will be cause of damage and so the treatment phase of acclimatization will be more accurate.

The light for the fish in bags is a major source of stress because it keeps them "awake" by stimulating the metabolism.

For these reasons the packaging will isolate bags from direct sunlight, so that temperature remains as constant as possible.

·     The internal factors are: oxygen, carbon dioxide, pH, salinity and ammonia.

Oxygen is injected into the bag, so it is available only a limited quantity. However  it is not the most important cause of problems during the transport.

Carbon dioxide is produced by the breathing. It is present in water both in dissolved form and  associated form, where the water becomes carbonic acid. In the first case is directly toxic at concentrations above 0.25 mg / l. In the second case interferes with the lowering of the pH value, greater is the effectiveness of acidification, lower is the value of the KH of the water transport.

Salts increase due to fish metabolism.

The ammonia is produced by fish and it is present  in the bag in the form of ammonium - ammonia or in the form of nitrite. Its concentration it is one of the most important cause of problems during the transport, for this reason it is necessary to "bleed" fishes before bagging, to avoid that water will be polluted by food or excrements.

“Perfect” acclimation allows us to eliminate as quickly as possible toxic substances (ammonia, nitrites, dissolved carbon dioxide) and at the same time to change as slowly as possible those factors which, if changed too quickly, could cause serious damage to fish metabolism (temperature, pH, salt content).

A drastic and rapid elimination of ammonia, nitrite and carbon dioxide immediately brings benefits because these substances are no longer absorbed by the body and don’t "pollute" metabolic processes.

A quick change of pH can be harmful for two reasons:

- in an acid environment of transport, fishes could absorb ammonia into the cellular tissues: when  the pH of the environment becomes basic,  it can turn into toxic ammonia and poison fishes;

- if ammonium is still present in the water of acclimation, it will turn into ammonia with the increase of pH and poison fishes.

Both a quick increase and decrease of temperature may be harmful:  in a case because the pathogens are "wake up" before the immune system attacking the fish without it supplies the correct answer, in the other case they will become too aggressive.

A rapid elimination of associated carbon dioxide can cause a rapid increase in pH value with the problems explained previously.

Let’s see now procedures at arrival of new guests:

- if in tank of destination are present some fishes, food them;

- turn off  lights of the aquarium and those of the room where we will open the packaging;

- open the external box and wait for 10-15 minutes to avoid that rapid changes of light can increase the stress to the newcomers

- measure the temperature of the water-transport and adjust the temperature of the tank destination if it is too different, but only in the case that the tank does not contain other guests;

- measure the pH of the water-transport to obtain the right reference parameter;

- check, with an appropriate test, if there is ammonia in the water of bags. If so and if the pH value is enough acid, eliminate the most part of water transport and integrate with the new ammonia free, with a salt content, temperature and pH similar to that of transport.

If we know the kind of water used by the seller during the shipment, we will be able to prepare in advance the water that we will use during the acclimatization. The pH can be lowered to the desired level using an acid like TetraAqua pH / KH Minus. This type of acidifying agent works on the carbonate hardness and low rapidly the pH which will rise slowly.

To stimulate the process of slow increase of pH, it is possible to introduce a air stone driven by an air pump during the phase of acclimatization.

It is very important that the pH value increase slowly, because in this way fishes are able to  remove ammonia from their body. Also zeolite can be used to remove ammonia adding it in water transport for 20g/l.

It will be necessary to proceed in the same way if temperature of the water transport is very different from that of aquarium. If the temperature is different for more than 2 ° C, increase it no faster than 1 ° every 10 minutes.

If, however, water transport is free of ammonium-ammonia is also possible effect the acclimatization in this water.

So, it will be important to check the pH and temperature. In this case, is sufficient an air stone that removes carbon dioxide, and slowly increases the pH. In addition, a slow supply of water from the aquarium will bring the temperature to the desired levels or it is possible put afloat the bag in the aquarium waiting until the temperature between the two systems is equal.

It is very important  to analyze and know the type of environment (water) in which new discus arrived. With a correct acclimatization fishes will certainly have fewer problems in all other phases that will bring them to become accustomed to their new environment.

Andrea A. Sassi

SGDiscus.com © All rights reserved

 It is prohibited to reproduce, also in part, illustrations, text and photos of this article, without permission.