1. Water Quality Issues: Poor water quality, including pollution from agricultural runoff, industrial waste, or untreated sewage, can negatively affect aquatic ecosystems and lead to fish die-offs.

2. Hypoxia: Oxygen depletion in the water, known as hypoxia, can occur due to various factors, including excessive nutrient runoff, leading to algal blooms that consume oxygen and create low-oxygen “dead zones” where fish cannot survive.

3. Harmful Algal Blooms (HABs): Certain types of algae can produce toxins during blooms, known as harmful algal blooms (HABs), which can poison fish and other marine organisms, leading to mass mortalities.

4. Disease Outbreaks: Outbreaks of infectious diseases can spread among fish populations, causing mass die-offs. Viral, bacterial, or parasitic infections can be triggered by various factors, including stress, overcrowding, or compromised immune systems.

5. Natural Events: Natural events such as storms, hurricanes, or fluctuations in water temperature and salinity can disrupt fish populations and cause mortality.

To understand the specific causes and environmental impact of the fish die-off in Texas, it is advisable to refer to local news sources, official reports from environmental agencies, or statements from relevant experts who are actively investigating the incident. They would have the most accurate and up-to-date information regarding the event and its implications for the local ecosystem.