Hatchery de langostino M. rosembergii, Oaxaca.
Km 204.5 Carretera federal 200, tramo Huatulco-Puerto Escondido, Col. Llano Grande Codigo Postal. 70946 Santa María Tonameca, México

No! Los antibióticos!

Preparando a Moqueca das Visitas...

http://www.aquafeed.com//Australia-government-invests-in-/

Los morfotipos durante el ciclo de cultivo.

Biofloc Technology

Ammonia in Aquaculture pond and how to control it? ------------------------------------------------------------------ Of all the water quality parameters that ...affect and influence fish behaviour and health, ammonia is one of the most important. Within an aquatic environment, ammonia occurs in two forms: ionized ammonia is relatively non-toxic and has the chemical formula NH4+, the toxic un-ionized form of ammonia has no charge and has the chemical formula NH3. The form of ammonia present at any given time is dictated by the water temperature and the pH, with rising alkaline conditions often preceding an increase in the toxic un-ionized ammonia levels. Ammonia plays an important part within the nitrogen cycle of any aquatic environment. This is the oxidative process in which ammonia is first converted into nitrite (NO2) by naturally occurring Nitrosospira and Nitrosomonas bacteria in the water, before further bacterial species Nitrospira and Nitrobacter convert the nitrite into nitrate (NO3). This nitrification process occurs either on the surface of the mud substrate and plants or within the biofilter of a tank based system. The nitrite is still toxic to fish species but encourages the growth and colonisation of Nitrobacter to convert it to the less toxic nitrate form. The nitrate is then taken up by aquatic plants and algae in aquaculture systems. The nitrogen cycle is directly influenced by oxygen and alkalinity levels, with a decrease in either terminating the cycle and thus increasing ammonia and nitrite levels once more. It is worth noting that the ammonia levels favour the growth of specific phytoplankton and algal species, which alters the aquatic biodiversity and dynamics of an ecosystem. Ammonia enters the aquatic environment primarily from the fish themselves via their waste. Fish diet will often contain high levels of protein, which when metabolised, produces ammonia as a by-product. The fish then excrete the ammonia from its blood into the water via a partial pressure gradient across its gill epithelium, as well as a small amount in the urine.The dietary protein concentration in the feed is directly proportional to the ammonia levels produced, with higher protein levels producing more ammonia. Other sources can include the decomposition of algae or uneaten food in the aquatic environment, with smaller volumes of water more susceptible to ammonia spikes. Ammonia ‘sinks’ occur within pond aquaculture in the form of the plants and algae. These organisms require nitrogen as a key nutrient for growth, and as a result absorb ammonia from the water. As rates of photosynthesis increase, plant and algal growth increases and the uptake of ammonia increases. Whilst the presence of algae within an aquaculture system does directly cause a reduction in ammonia levels, it is not a viable long-term method for ammonia removal. Algal blooms are also subject to crashing, whereby the algae population, without explanation, dies suddenly. In such instances, the algal matter reverts from a sink to a source of ammonia, as well as reducing the dissolved oxygen concentrations and pH and increasing the levels of carbon dioxide present. Effect of higher concentration of Ammonia : Ammonia affects the fish both directly and indirectly depending on the levels present, with certain species more susceptible to ammonia toxicity than others. At lower concentrations, around 0.05mg/L, un-ionized ammonia is harmful to fish species and can result in poor growth and feed conversion rates, reduced fecundity and fertility and increase stress and susceptibility to bacterial infections and diseases. At higher concentrations, exceeding 2.0mg/L, ammonia causes gill and tissue damage, extreme lethargy and death. Excess feed is one of the primary sources of ammonia build up, but reducing feeding rates is not a short-term solution and will have little immediate effect. In order to reduce the risks in the long-term and to minimise the associated effects of sub-lethal ammonia exposure, a managed conservative feeding rate with monitored protein content should be implemented, and adjusted seasonally. Feeding during periods of stress will further exacerbate the issue, as food will remain uneaten and contribute to elevated ammonia levels. The addition of lime or phosphorus is another option. Adding a liming agent can work to correct extreme pH values, and is often implemented during late afternoon when the toxic form is likely to be at its highest. This method does not act to remove the ammonia, but rather alters the ammonia form present from toxic to non-toxic in low pH conditions. In fact, the addition of lime into ponds with adequate alkalinity may cause a rapid pH shift and only serve to compound the ammonia issue. Phosphorus acts as a fertiliser for algae, increasing the algal population and in consequence the uptake of ammonia. Other solutions include increasing aeration within a pond and flushing with freshwater. By aerating a pond, dissolved ammonia in the toxic form will diffuse from the water into the air. Increasing aeration may serve to stir the benthic sediment and thus increase the ammonia levels further. Flushing through with new water is effective to reduce ammonia levels in small ponds . But it is difficult in large area. Use of Probiotics and geolite is also effective to control ammonia. But in large scale aquaculture it is expensive. In an aquaculture environment, particularly on a larger scale, there is no fast acting remedy to elevated ammonia levels, and it is the prevention rather than the correction that should be the focus, with regular monitoring a key component.

A las brazas...!

PREBIOTICOS USADOS EN EL ALIMENTO PUEDEN POTENCIAR LA SUPERVIVENCIA DEL CAMARÓN

Gulai lemak Kome petang ni

GIANT PRAWN 2019 second day and farm tour. The next global freshwater prawn conference, GIANT PRAWN 2022 has also been announced at the venue. GIANT PRAWN 2022 will be held at AIT, Bangkok from 14-17 March 2022. Preliminary announcement will be released soon!